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ILLINOIS  STATE 
NATURAL  HISTORY  SURVEY 
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Digitized  by  the  Internet  Archive 
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https://archive.org/details/phytoplanktonofi5711smit 


WISCONSIN  GEOLOGICAL  AND  NATURAL  HISTORY  SURVEY 

W.  O.  HOTCHKISS.  Director 


BULLETIN  NO.  57  SCIENTIFIC  SERIES  NO.  12 


Phytoplankton  of  the  Inland 
Lakes  of  Wisconsin 


Part  I 

Myxophyceae,  Phaeophyceae,  Heterokonteae,  and 
Chlorophyceae  exclusive  of  the  Desmidiaceae. 


BY 

GILBERT  MORGAN  SMITH 


MADISON,  WIS. 

Published  by  the  State 
1920 


Wisconsin  Geological  and  Natural  History  Survey 


BOARD  OF  COMMISSIONERS. 

EMANUEL  L.  PHILIPP, 

Governor  of  the  State. 

EDWARD  A.  BIRGE,  President. 

President  of  the  University  of  Wisconsin. 

President  of  the  Wisconsin  Academy  of  Sciences,  Arts,  and  Letters. 

CHARLES  P.  CARY,  Vice-President. 

State  Superintendent  of  Public  Instruction. 


STAFF  OF  THE  SURVEY,  1919. 

/^ADMINISTRATION: 

William  0.  Hotchkiss,  State  Geologist,  Director  and  Superintendent. 

In  immediate  charge  of  Geology  Division. 

Ernest  P.  Bean,  Assistant  State  Geologist. 

Lillian  M.  Veerhusen,  Chief  Clerk. 

Frances  Walker,  Clerk  and  Stenographer. 

Angeline  Doll,  Clerk. 

GEOLOGY  DIVISION: 

William  0.  Hotchkiss,  In  charge. 

Ernest  P.  Bean,  Geologist,  Mineral  Land  Classification. 

T.  C.  Chamberlin,  Consulting  Geologist,  Pleistocene  Geology. 

E.  O.  Ulrich,  Consulting  Geologist,  Stratigraphy,  by  cooperation  of  the 
U.  S.  G.  S. 

H.  R.  Aldrich,  Geologist. 

Clare  Gillis,  Geologist. 

R.  H.  Whitbeck,  Geographer. 

T.  J.  Dunnewald,  Field  Assistant  and  Analyst. 

P.  T.  Thwaites,  Geologist,  Well  Records,  Educational  Rock  Collection. 

NATURAL  HISTORY  DIVISION: 

Edward  A.  Birge,  In  charge. 

Chancey  Juday,  Lake  Survey. 

DIVISION  OF  SOILS: 

A.  R.  Whitson,  In  charge. 

W.  .1.  Geib,  Inspector  and  Editor. 

M.  .1.  Dunnewald,  Field  Assistant  and  Analyst. 

H.  W.  Stewart,  Pheld  Assistant  and  Physicist. 


557 
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TABLE  OF  CONTENTS 


Preface  

Introduction  

List  of  lakes  investigated  . . , 
Analytical  key  to  the  genera 

Myxophyceae  

Phaeophyceae  

Heterokonteae  

Chlorophyceae 


Page 

1 

5 


J.3 


21 


26 


65 


79 


88 


1 300  I 6 


PREFACE 


The  general  name  plankton  is  given  to  the  organisms  which  live  iree- 
floating  in  the  deeper  parts  of  lakes  and  ponds;  the  plant  individuals 
being  designated  the  phytoplankton  and  the  animal  the  zooplankton. 
Investigations  have  shown  that  there  is  a very  special  algal  flora  liv- 
ing exclusively  in  the  plankton,  in  addition  to  the  chance  wanderers 
from  the  littoral,  or  marginal,  region  which  do  not  multiply  when  in 
the  plankton.  These  will  be  designated  as  the  euplanktonts  and  tycho- 
planktonts  respectively  in  this  work.  There  is  still  another  group  of 
organisms  found  in  lakes,  namely  those  which  thrive  equally  under 
littoral  or  pelagic  conditions.  This  group  will  be  referred  to  as  the 
facultative  planktonts.  Attempts  have  been  made  to  differentiate  be- 
tween organisms  of  these  three  groups  by  the  Wests,  Telling,  and 
others,  although  a different  terminology  has  been  used.  Since  the 
question  of  a proper  habitual  classification  for  any  particular  species 
will  always  be  a matter  of  individual  opinion,  I have  indicated  at  the 
end  of  the  description  my  conception  of  the  natural  habitat  of  the 
organisms  found  in  the  lakes  of  this  state. 

It  is  only  within  the  past  twenty -five  years  that  the  phytoplankton  has 
been  studied,  and  our  knowledge  of  the  various  members  constituting 
this  specialized  flora  has  come  almost  exclusively  from  European  phyco- 
logists.  William  West,  G.  S.  West  and  Pritsch  in  England;  Chodat 
and  Bachmann  in  Switzerland ; Lemmermann,  Schmidle,  Schroder  and 
Volk  in  Germany;  von  Keissler,  Pascher  and  Woloszynska  in  Austria- 
Hungary;  and  Wesenberg-Lund  in  Denmark  have  been  the  chief  stu- 
dents of  European  phytoplankton.  The  central  African  lakes  have 
been  investigated  by  G.  S.  West,  Schmidle,  and  Woloszynska.  G.  S. 
West  and  Playfair  have  studied  the  phytoplankton  of  Australia.  With 
the  exception  of  Miss  Snow’s  work  on  Lake  Erie  nothing  was  known 
concerning  the  taxonomy  of  North  American  phytoplankton  at  the 
time  the  present  work  was  undertaken,  the  pioneer  work  on  the  micros- 
copy of  the  Massachussetts  and  Brooklyn  water  supplies  being  of  little 
value  to  the  systematist  since  determinations  were  not  carried  beyond 
the  genus. 

These  studies  of  Wisconsin  lakes,  carried  out  under  the  auspices  of 
the  Wisconsin  Geological  and  Natural  History  Survey,  were  commenced 
in  the  fall  of  1913.  Field  work  was  continued  during  the  summers  of 


2 


PREFACE 


1914-15-16-17  and  all  lake  areas  of  the  state  have  been  visited  during 
the  progress  of  the  investigation.  Collections  have  been  made  from 
the  lakes  around  Madison  and  Oconomowoc  during  the  entire  season 
that  they  are  open.  The  June,  August  and  early  September  flora  of 
the  northeastern  lakes  is  represented,  while  the  northwestern  lakes  were 
visited  for  two  successive  seasons  during  August.  Only  single  collec- 
tions were  made  from  the  northern  lakes  so  that  the  data  for  any  par- 
ticular one  of  them  are  undoubtedly  very  fragmentary. 

The  limits  of  the  survey  are  determined  by  the  political  boundaries 
of  the  state  and  not  by  ecological  or  regional  unity.  There  is  a con- 
tinuation of  the  southeastern  lake  group  in  northeastern  Illinois;  of 
the  northeastern  lake  group  in  the  northern  peninsula  of  Michigan ; and 
of  the  northwestern  lake  area  in  Minnesota.  However,  variation  in 
depth  and  surface  area  together  with  variation  in  chemical  content  of 
Wisconsin  lakes  gives  a sufficient  range  of  habitat  to  cover  conditions 
found  in  almost  all  other  parts  of  the  world  if  temperature  and  altitude 
are  excluded.  The  cosmopolitan  nature  of  phytoplankton,  therefore, 
makes  this  work  of  value  to  the  student  of  these  microorganisms  in 
other  sections  of  the  United  States  or  even  other  continents,  and  he  will 
probably  find  a majority  of  the  species  in  any  region  represented  in 
the  Wisconsin  flora.  There  is  a temptation  to  include  species  that  have 
not  been  observed  in  order  to  round  out  the  work  for  the  student  in 
other  parts  of  the  world.  This  practice  has  been  followed  in  certain 
algal  floras  and  while  it  may  be  helpful  to  the  general  student,  it  causes 
endless  confusion  to  the  phytogeographer.  Only  those  species  are  in- 
cluded in  this  flora  which  have  been  collected  from  the  state. 

Descriptions  of  plankton  algae  are  scattered  through  a large  number 
of  periodical  publications  and  transactions  of  learned  societies,  many 
with  only  a limited  circulation,  so  that  considerable  effort  has  been 
spent  in  giving  full  and  correct  citations  for  the  original  descriptions. 
When  subsequent  descriptions  have  been  better  or  have  given  more 
characteristic  figures  references  are  also  made  to  theiti.  A great  deal 
of  time  has  also  been  spent  making  camera  lucida  drawings  since  an 
accurate  figure  is  frequently  more  valuable  than  a description.  Draw- 
ings of  the  various  species  of  a genus  are  generally  on  the  same  scale, 
but  there  has  been  no  attempt  to  draw  the  different  genera  on  the  same 
scale.  The  finer  details  of  cytological  structure,  such  as  the  nature  of 
the  chloroplast  or  structure  of  the  pyrenoid,  are  frequently  lost  in  pre- 
served material ; so  all  of  the  Chlorophyceae,  with  the  exception  of  the 
Desmidiaceae,  the  Phaeophyceae,  Heterokonteae  and  the  Myxophyceae, 
have  been  drawn  from  living  material. 

The  original  plan  for  the  study  of  Wisconsin  lake  algae  included  those 
attached  to  rocky  shores  or  lying  among  the  macroscopic  vegetation  in 
the  quieter  portions  of  lakes  in  order  to  get  the  relation  between  the 


PREFACE 


3 


benthos  and  the  plankton,  but  it  soon  became  apparent  that  limitations 
of  both  time  and  space  precluded  an  adequate  presentation  of  the  lit- 
toral flora;  attention,  therefore,  has  been  confined  to  phytoplankton 
since  the  second  season  ^s  work.  The  great  amount  of  material  on  the 
phytoplankton  has  necessitated  dividing  the  work  into  two  portions; 
the  material  included  in  the  present  volume,  and  the  Desmidiaceae  and 
Bacillareae  which  are  reserved  for  a later  one.  A considerable  amount 
of  work  has  been  done  already  on  these  two  groups  and  it  is  hoped  that 
the  complete  report  can  be  published  shortly. 

Phycologists  are  generally  agreed  on  the  broader  principles  of  algal 
classification  but  naturally  differ  on  minor  details.  The  classification 
here  adopted  for  the  Myxophyceae  is  used  almost  universally.  The 
group  of  flagellates  with  brown  chromatophores  is  frequently  consid- 
ered more  animal  than  plant.  One  section,  the  Chrysomonadineae, 
where  there  are  golden  brown  chromatophores,  seems  to  be  sufficiently 
related  to  the  Phaeophyceae  to  warrant  placing  them  in  a description 
of  plankton  algae  and  in  the  arrangement  of  the  group  I have  followed 
Pascher’s  classification.  Since  Luther’s  establishment  of  the  Hetero- 
konteae,  the  question  of  whether  to  recognize  this  group  as  a separate 
class  or  a division  of  the  Chlorophyceae  has  arisen.  The  evidence 
seems  fairly  clear,  however,  that  the  origin  of  the  group  is  from  a 
primitive  flagellate  of  the  Chloramoeha  type  and  since  this  phylogenetic 
starting  point  is  so  markedly  different  from  the  phylogenetic  starting 
point  of  the  Chlorophyceae  (the  Polyblepharidaceae)  I feel  that  the 
two  should  be  considered  distinct  classes.  The  classification  used  is 
that  of  G.  S.  West,  although  it  should  be  noted  that  he  considers  the 
Heterokonteae  a division  of  the  Chlorophyceae.  I have  also,  with  a 
few  exceptions,  followed  West’s  arrangement  of  the  Chlorophyceae. 
It  is  hoped  that  the  keys  found  in  this  work  will  prove  usable.  They 
are  based  solely  upon  characters  of  the  species  described  herein;  so 
will  be  of  no  value  for  those  not  mentioned. 

During  the  seasons  of  1916  and  1917  the  field  work  was  assisted  by  a 
grant  of  money  from  the  United  States  Bureau  of  Fisheries;  and  the 
extension  of  these  studies  to  the  lakes  of  northwestern  Wisconsin  has 
thus  been  made  possible. 

The  University  of  Wisconsin, 

Department  of  Botany, 

February,  1919. 


INTEODUCTION 


Geography  and  geology  of  Wisconsin.  The  state  of  Wisconsin  lies 
between  Lake  Superior,  Lake  Michigan  and  the  Mississippi  river  and 
has  an  area  of  56,066  square  miles,  cr  an  area  somewhat  larger  than 
England.  Its  greatest  breadth  is  about  295  miles  and  greatest  length 
320  miles.  Within  its  borders  are  numerous  lakes,  the  total  number 
probably  reaching  well  into  the  thousands,  with  an  estimated  surface 
area  of  about  1500  square  miles.  They  vary  in  size  from  small  lakelets 
and  ponds  that  cover  but  a few  acres,  to  Lake  Winnebago  with  an 
area  of  215  square  miles.  The  great  majority  of  the  lakes,  however, 
have  less  than  a square  mile  of  surface  area.  There  is  likewise  great 
variation  in  depth,  but  for  the  most  part  they  are  shallow  since  the 
deepest  (Green  Lake)  has  a maximum  depth  of  237  feet  and  only  a 
few  have  a depth  of  over  a hundred  feet.  Certain  phycologists  have 
tried  to  differentiate  between  the  plankton  floras  of  ponds  (heleoplank- 
ton)  and  lakes  (limnoplankton).  The  lakes  of  this  state  grade  so  im- 
perceptibly from  the  ‘‘pond’’  to  the  “lake”  type  that  it  has  been  im- 
possible to  distinguish  between  the  two.  To  set  arbitrarily  a surface 
area  of  a square  mile  and  depth  of  25  feet  as  the  maximal  limits  for  a 
pond  would  involve  many  difficulties ; since  the  state  presents  such  ex- 
amples as  Beasley  Lake  with  a surface  area  of  0.019  square  miles  and 
a depth  of  51  feet  or  Lake  Winnebago  with  a surface  area  of  215  square 
miles  and  a maximum  depth  of  21  feet.  I have,  therefore,  listed  all 
bodies  of  water  as  lakes  but  have  given,  in  Table  2,  all  available  data 
on  area  and  depth  for  those  desiring  to  recapitulate  into  heleoplank- 
ton  and  limnoplankton. 

There  are,  roughly  speaking,  three  lake  areas  in  the  state ; the  south- 
eastern, northwestern  and  northeastern,  all  of  which  owe  their  origin 
to  glaciation.  These  lake  areas  are  not  uniformly  distributed  over  the 
state  since  the  glacier  invading  this  region  was  divided  into  lobes  and 
lakes  are  found  in  greatest  abundance  along  the  terminal  and  kettle 
moraines  of  these  various  lobes.  The  southwestern  portion  of  the  state 
possesses  no  lakes  since  it  lies  in  a non-glaciated  region.  The  south- 
eastern lake  area  includes  several  scattered  moderately  sized  lakes  and 
groups  of  smaller  lakes  some  of  which  are  among  the  deepest  in  the 
state.  The  majority  of  them  lie  in  a region  of  kames  and  pitted  plains, 
where  the  pits  and  lake  basins  owe  their  origin  to  the  burial  and  sub- 


6 


INTRODUCTION 


sequent  melting  of  large  irregular  blocks  of  ice.  The  Oconomowoc, 
Lauderdale  and  Waupaca  lake  groups  are  of  this  type.  A few  of 
the  larger  and  deeper  lakes,  as  Green  and  Mendota,  are  situated  in 
valleys  eroded  by  preglacial  streams  that  were  possibly  modified  by 
glacial  action  and  then  closed  by  the  building  of  a morainal  dam  which 
impounded  the  waters  of  the  present  lake. 

The  northeastern  lake  group  lies  chiefly  in  Vilas,  Oneida  and  Iron 
counties.  There  are  hundreds  of  lakes  in  this  area  and  their  closeness 
of  position  may  readily  be  inferred  from  the  fact  that  while  the  largest 
of  them,  Trout  Lake,  covers  only  6.5  square  miles  the  346  lakes  and 
ponds  in  Vilas  county  occupy  140  square  miles  or  over  15  percent  of 
the  area  of  a county  nearly  as  large  as  Rhode  Island.  In  few  parts  of 
the  world  are  there  more  lakes  to  the  square  mile.  Parts  of  the  State 
of  Minnesota,  the  Province  of  Ontario,  and  Finland  furnish  the 
only  parallel.  These  lakes  are  small,  irregularly  shaped,  and  connected 
by  streams  with  most  irregular  courses.  They  are  all  glacial  in  origin 
and  formed  either  by  shallow  depressions  of  the  ground  moraine,  hol- 
lows in  outwash  plains,  or  damming  of  recessional  moraines.  > The  en- 
tire region  is  so  deeply  buried  by  the  glacial  drift  that  no  lake  is  due 
to  a damming  of  a preglacial  valley.  This  entire  region  also  contains 
numerous  swamps  (muskegs)  characteristics  of  a poorly  drained  area. 

The  northwestern  lake  area  lies  in  Barron,  Polk,  Burnett,  Washburn, 
and  Sawyer  counties.  In  general  it  is  similar  to  the  northeastern  lake 
area  in  structure  and  origin  but  the  lakes  do  not  occupy  so  great  a 
portion  of  the  land’s  surface.  It  has  been  suggested  that  some  of  the 
lakes  in  this  region  were  formed  before  the  last  glacial  invasion  or  Late 
V/isconsin  glacial  epoch.  Here  we  find  a few  lakes  formed  by  a dam- 
ming of  preglacial  valleys;  Bone,  Beaverdam,  and  Wapagossett  lakes 
for  example. 

The  mean  average  temperature  of  Wisconsin  varies  from  6.6°  C.  in 
the  southern  portion  to  3.3°  C.  in  the  northern.  The  state  has  a mean 
summer  temperature  similar  to  that  of  Prance,  Germany,  or  south- 
eastern England  (14.5°  to  18°)  ; the  average  winter  temperature  is  com- 
parable to  that  of  northern  Sweden  or  central  Russia  (-5.4°  to  -8.8°). 
All  lakes  in  the  state  are  frozen  over  during  the  winter,  ice  forming 
during  November  and  December  and  lasting  until  March  or  April  in 
the  southern  ones,  while  on  some  of  the  northern  lakes  ice  appears  in 
October  and  remains  until  the  latter  part  of  May.  The  midsummer 
surface  temperature  of  the  northern  lakes  is  18°-24°  C.  and  20°-26^ 
in  the  southern  lakes. 

The  altitude  of  the  lakes  in  the  northeastern  part  of  the  state  varies 
from  1550-1700  feet  above  sea  level;  in  the  northwestern  area  1050- 
1350  feet,  and  from  750  to  900  feet  in  the  southeastern.  These  differ- 
ences in  elevation  ai*e  too  slight  to  be  of  any  biological  significance. 


INTRODUCTION 


7 


Likewise  differences  in  the  amount  of  mean  annual  precipitation,  which 
j’ange  from  28-44  inches  in  various  parts  of  the  state,  need  no  discus- 
sion since  rainfall  in  all  regions  is  sufficient  to  maintain  lakes  at  their 
normal  level. 

The  underlying  geological  formations  are,  however,  of  prime  import- 
ance and  have  a marked  influence  on  the  distribution  of  plankton  or- 
ganisms, especially  the  plankton  desmids.  Within  the  state  are  found 
areas  of  igneous,  metamorphic,  and  sedimentary  rocks  each  of  which 
have  a different  direct  influence  on  the  chemical  environment  of  the 
plankton  organisms.  The  underlying  rock  formations  of  the  south- 
eastern lake  area  are  the  Niagara  limestone  of  the  Silurian;  the  Cin- 
cinnati shale.  Galena  limestone.  Lower  Magnesian  limestone  and  St. 
Peter  sandstone  of  the  Ordovician.  In  the  northwestern  lake  region 
is  found  the  Cambrian  Potsdam  sandstone,  the  Ordovician  Lower  Mag- 
nesian limestone,  together  with  areas  of  Keeweenawan  trap  rock  and 
Precambrian  granites.  The  northeastern  area  is  entirely  Precambrian 
granites. 

Overlying  all  of  these  regions  is  a mantle  of  glacial  drift  some  of 
which  is  local  in  origin  while  other  constituents  have  been  transported 
from  distant  regions.  This  ground  moraine  in  southeastern  Wisconsin 
varies  in  thickness  from  a few  feet  on  hill  tops  to  over  400  feet  in  the 
bottom  of  preglacial  valleys.  Mechanical  analyses  show  that  13%  con- 
sists of  crystalline  rocks  transported  from  Canada  while  the  remaining 
87%  is  local  sand-  and  limestone.  In  the  northeastern  lake  area  the 
glacial  mantle  varies  from  75-100  feet  in  thickness  with  a maximum 
depth  of  350  feet  at  the  southern  boundary  of  the  area.  This  glacial 
accumulation  is  not  the  result  of  one  ice  invasion  but  of  several;  the 
last,  and  the  one  which  left  the  most  material,  came  from  the  north- 
east and  transported  the  conspicuous  sand  deposits  of  Vilas  and  north- 
ern Oneida  counties  from  the  sandstone  region  of  northern  Michigan. 
Previous  ice  invasions  came  from  the  northwest  and  their  deposits,  in 
some  instances,  have  not  been  disturbed  by  succeeding  invasions.  None 
of  the  drift  in  this  region  is  calcareous  so  that  all  soils  are  acid  in 
character.  The  mantle  of  drift  in  the  northwestern  area  varies  from 
500  to  a few  feet  in  thickness  and  is  composed  of  material  from  granitic 
and  sandstone  regions.  There  is,  however,  a certain  amount  of  lime 
in  the  drift  at  the  southern  limit  of  the  lake  area. 

Chemical  composition  of  the  lake  waters.  Birge  and  Juday*  have 
made  investigations  on  the  chemical  composition  of  the  waters  of  Wis- 
consin lakes  in  connection  with  their  biochemical  studies.  They  divide 
the  waters  into  three  general  classes;  soft,  medium,  and  hard.  These 


* Birge,  E.  A.  and  Juday,  C.  The  inland  lakes  of  Wisconsin.  The  dissolved 
gases  of  the  water  and  their  biological  significance.  Bull.  22  Wis.  Geol.  and 
Nat.  Hist.  Survey.  (Sci.  Ser.  7.)  pp.  1-259.  1911. 


8 


INTRODUCTION 


varying  degrees  of  hardness  are  due  to  the  combination  of  the  carbon 
dioxide  with  calcium  and  magnesium  to  form  carbonates,  the  fixed 
(CaCOg  and  MgCOg)  and  the  half-bound  (CaCOg.HgCOg  and 
MgCOg.HaCOg).  In  neutral  and  acid  lakes  the  two  types  of  carbon 
dioxide  are  present  in  equal  amounts  but  in  alkaline  lakes  there  is  an 
excess  of  fixed  carbon  dioxide.  This  is  due  to  the  ability  of  the  chloro- 
phyll bearing  organisms  to  draw  upon  the  half-bound  carbon  dioxide 
as  a source  of  supply  after  the  disappearance  of  the  free  carbon  diox- 
ide. The  amounts  of  magnesium  and  calcium  vary  from  lake  to  lake 
and  there  is  an  almost  continuous  series  from  those  having  the  softest 
waters  to  those  having  the  hardest.  They  consider  those  lakes  whose 
average  fixed  carbon  dioxide  does  not  exceed  5 cc.  per  liter  as  soft 
water  lakes,  while  medium  waters  have  6-22  cc.  of  carbon  dioxide  per 
liter  and  the  hard  waters  from  23-50  cc.  per  liter.  The  carbon  dioxide 
content  varies  with  the  depth  at  which  the  sample  is  taken  and  also 
with  the  season  of  the  year;  some  of  the  medium  class  lakes,  for  ex- 
ample, have  a sufficiently  low  content  at  times  to  qualify  as  soft  water 
lakes.  All  of  the  soft  and  medium  waters,  with  the  exception  of  Devils 
lake  in  Sauk  county,  are  located  in  the  northeastern  and  northwestern 
lake  areas  and  many  of  them  have  sufficient  free  carbon  dioxide  to 
give  an  acid  reaction  with  phenolphthalein.  The  hardwater  lakes  are 
all  in  the  southeastern  area  and  the  upper  stratum  in  them  is  alkaline 
to  phenolphthalein  for  the  greater  part  of  the  year. 

Aside  from  the  question  of  the  hardness  of  the  water  complete  min- 
eral analyses  of  a few  lakes  are  also  available.  These  results  are  em- 
bodied in  Table  1 and  represent  average  conditions.  They  are  taken 
from  the  data  given  by  Birge  and  Juday  and  their  data  show  that 
there  is  a seasonal  variation  and  a vertical  variation  in  the  amounts  of 
certain  elements  present.  These  variations  in  vertical  distribution  are 
well  shown  in  their  Fig.  7,  p.  106  (1.  c.)  The  lakes  of  southeastern 
Wisconsin  contain  a rich  flora  of  Chlorophyceae,  Myxophyceae  and 
Phaeophyceae,  both  in  quantity  and  quality.  In  the  northern  lake 
areas  the  total  volume  of  the  plankton  is,  generally  speaking,  consider- 
ably smaller  and  quite  different  in  character.  These  lakes  have  a con- 
siderable desmid  flora  in  many  instances,  while  with  the  exception  of 
one  or  two  species  desmids  are  not  found  in  the  hard  waters  of  the 
southeastern  region.  The  volume  of  phytoplankton  that  can  be  pro- 
duced in  a lake  is  primarily  dependent  upon  the  available  supply  of 
carbon  dioxide  for  photosynthesis.  In  the  northern  lakes  this  supply 
is  chiefly  the  carbon  dioxide  dissolved  in  the  water  but  in  the  southern 
lakes  there  is  in  addition  considerable  quantities  of  half -bound  carbon 
dioxide  which  may  be  drawn  upon  after  the  free  carbon  dioxide  is  ex- 
hausted. It  is  not  surprising,  therefore,  that  the  southern  lakes  with 
greater  supplies  of  potential  food  materials  have  a greater  production 


INTRODUCTION 


9 


of  algae.  There  are  certain  factors  modifying  the  growth  of  algae  in 
hard  water  lakes ; in  those  deep  ones  which  become  thermally  stratified 
in  the  summer  most  of  the  algae  are  restricted  to  the  epilimnion.  The 
thickness  of  the  epilimnion  is  in  part  dependent  upon  the  size  and  shape 
of  the  lake,  since  the  wind  is  more  effective  in  keeping  water  in  circula- 
tion on  large  surfaces.  Algae  are  continually  sinking  to  the  bottom  and 
giving  rise  to  carbon  dioxide  and  nitrogenous  products.  In  the  deep 


Table  1. — Results  of  mineral  analyses  stated  in  parts  per  million.  These  shoic 
aderage  content  of  m/nous  depths  and  at  different  dates. 


lakes  these  products  of  decay  are  chiefiy  in  the  hypolimnion  and  are 
not  immediately  available  for  reutiiization  by  other  algae.  In  shal- 
low lakes  without  thermal  stratification  these  products  are  immediately 
available  for  the  vegetative  activities  of  algae.  Shallow  lakes,  there- 
fore, support  proportionally  larger  algal  floras.  The  restriction  of 
the  desmids  to  the  soft  water  lakes  was  first  pointed  out  by  the  Wests 
and  their  observations  have  been  confirmed  in  Wisconsin  (Birge  and 
Juday,  1.  c.  p.  138).  An  examination  of  the  chemical  analyses  of  such 
soft  water  lakes  as  Devils,  Trout  and  Kawaguesaga  (Table  1)  shows 
that  in  these  lakes  which  contain  numerous  desmids  the  calcium  and 
magnesium  content  is  relatively  small.  The  influence  of  calcium  and 
magnesium  on  the  distribution  of  desmids  may  be  that  of  a direct  in- 
hibition of  growth  or  the  absence  of  these  elements  may  permit  an 
acid  condition  which  is  favorable  for  the  growth  of  desmids.  Data  on 
organic  matter  and  distribution  of  nitrogen  in  lakes  of  the  state  are 
lacking.  The  scarcity  or  abundance  of  available  nitrogen  is  doubtless 
an  important  factor  in  the  volume  of  algae  produced  in  a lake,  and  it 
is  a well  known  fact  that  as  regions  become  more  thickly  settled  and 
drainage  entering  the  lake  becomes  richer  in  nitrogenous  material  the 
growth  of  plankton  algae  becomes  more  luxuriant. 


10 


INTRODUCTION 


Methods  of  collection  and  study.  All  plankton  collections  have  been 
made  with  nets.  In  general  both  the  bolting  silk  net  and  the  cotton 
disc  net  were  used.  The  bolting  silk  net  of  No.  20  bolting  cloth  (new 
No.  25)  is  that  described  by  Juday*.  The  cotton  disc  net  is  made  by 
attaching  a filter  designed  for  purifying  drinking  water  (Jones  Mod- 
ern Filter  made  by  the  Jones  Mfg.  Co.,  Boston,  Mass.)  to  the  bottom 
of  an  eighteen  inch  cone  of  canvas  whose  mouth  is  held  open  by  a light 
metal  ring  ten  inches  in  diameter.  In  using  this  filter  a special  cot- 
ton disc  supplied  by  the  manufacturer  is  placed  in  the  filter  and  the 
whole  apparatus  drawn  through  the  water.  The  algae  collect  on  the 
disc  and  when  there  is  a sufficient  accumulation  the  disc  is  taken  from 
the  filter  and  shaken  in  a bottle  with  a small  amount  of  water  which 
removes  the  algae.  This  net  catches  many  of  the  smaller  organisms 
that  pass  through  the  bolting  silk  (the  nannoplankton)  and  it  is  also 
very  useful  in  obtaining  samples  by  dipping  when  no  boat  is  available. 
Whenever  possible  samples  have  been  gathered  by  towing  the  nets  at 
the  surface  and  all  collections  have  been  made  in  the  deep  parts  of  all 
lakes  to  avoid,  as  far  as  possible,  the  littoral  flora.  No  attempt  has 
been  made  to  study  the  vertical  distribution  of  the  algae  in  any  lake. 

In  studying  the  flora  of  any  region  a field  laboratory  was  established 
and  with  that  as  a center  excursions  were  made  to  the  surrounding 
lakes.  By  traveling  from  lake  to  lake  in  an  automobile  collections 
could  be  made  in  the  morning  and  the  material  studied  the  same  after- 
noon and  the  following  day.  In  the  northeastern  lake  area  where 
there  are  no  roads  in  many  cases,  but  where  lakes  are  close  together, 
they  can  be  visited  by  portaging  a canoe  from  lake  to  lake.  Collections 
have  been  made  from  row  boats,  where  they  were  obtainable,  but  in  a 
few  instances  collections  had  to  be  made  by  repeatedly  dipping  the 
net  after  wading  to  where  the  water  was  3-4  feet  deep  or  from  rafts. 
Upon  returning  to  the  temporary  laboratory  equipped  with  compound 
microscope,  camera  lueida,  and  drawing  materials,  the  living  specimens 
were  studied  and  numerous  pencil  camera  lueida  drawings  made  of  all 
doubtful,  interesting,  or  rare  organisms,  together  with  notes  on  occur- 
rence and  ocular  micrometer  measurements  of  known  forms.  No  ob- 
servations were  made  on  desmids  or  diatoms  at  this  time.  The  study 
of  the  Chlorophyceae,  Myxophyceae  and  Phaeophyceae  in  the  living 
condition  is  particularly  important  since  many  of  them  do  not  preserve 
well  and  certain  features  such  as  cilia,  chloroplasts,  and  contractile 
vacuoles  are  lost  when  material  is  preserved.  All  drawings  of  one 
species  are  mounted  on  the  same  sheet  and  corresponding  notes  on  an- 
other. The.se  ai-e  then  filed  in  species  and  genus  covers  in  the  usual 


* Juday,  C.  Limnological  apparatus.  Trans.  Wis.  Acad.  Sci.  Arts  & Lett. 
18^:  566-592.  1916. 


INTRODUCTION 


11 


manner  for  herbarium  specimens  so  that  all  data  on  any  particular  spe- 
cies are  immediately  accessible.  The  figures  for  the  plates  of  this  work 
have  been  redrawn  from  camera  lucida  sketches  made  in  field  labora- 
tories. The  confined  space  of  a vial  is  not  favorable  for  algae  and  the 
more  delicate  forms,  as  Uglenopsis,  frequently  go  to  pieces  after  stand- 
ing a few  hours.  It  is  impossible  to  have  the  vials  uncorked  while 
transporting  them  from  station  to  station  but  they  should  be  opened 
immediately  on  return  to  field  headquarters.  I have  also  found  it 
helpful  to  keep  them  as  cool  as  possible  and  have  stored  them  in  hotel 
refrigerators  until  ready  to  make  observations.  Formalin  has  proven 
a satisfactory  means  of  preserving  the  desmids  and  diatoms  until  their 
study  can  be  taken  up  during  the  winter  months. 

The  following  list  of  simple  reagents  is  helpful  in  studying  the  vari- 
ous structures  of  living  algae.  Cilia  of  motile  forms  are  more  easily 
seen  when  the  cells  have  been  rendered  immobile  by  mounting  in  a 1% 
cocaine  solution.  Mounting  in  a dilute  aqueous  acid  fuchsin  also  helps. 
Pyrenoids  can  be  recognized  by  the  grouping  of  the  starch  grains  when 
the  latter  have  been  stained  with  iodine.  It  is  difficult  to  strain  pyre- 
Roids  of  living  cells.  Gelatinous  envelopes  are  best  demonstrated  by 
Errera's  method  of  mounting  in  dilute  India  ink  which  gives  the  col- 
orless envelope  the  appearance  of  a halo  around  the  cells  in  contrast 
to  the  dark  background  of  water  containing  the  ink.  Nuclei  can  be 
demonstrated  by  Strasburger ’s  solution  of  methyl  green  in  1%  acetic 
acid.  Simple  microchemical  tests  are  Sudan  III  for  fats,  iodine  for 
starch,  zinc  chloriodide  for  cellulose,  and  Euthineum  Red  for  pectin. 

Lakes  studied.  The  following  table  gives  a list  of  lakes  in  the  state 
from  which  plankton  samples  have  been  taken.  All  known  hydro- 
graphic  maps,  morphometric  data,  general  descriptions  of  many  lakes 
and  general  maps  of  the  various  lake  areas  have  been  given  by  Birge 
and  Juday^'  so  that  any  one  wishing  further  data  concerning  a particu- 
lar lake  is  referred  to  their  work.  They  have  not,  however,  mapped  or 
discussed  many  of  the  smaller  lakes  of  the  northern  regions.  Since 
most  of  the  lakes  in  the  state  were  named  by  the  settlers  of  the  region 
considerable  poverty  of  vocabulary  is  noticed  and  Round,  Mud,  Devils, 
Long,  and  Sand  are  repeated  many  times.  In  other  instances  Indian 
(Chippewa)  names  have  been  retained  as  the  white  man  settled  the 
region.  In  these  also  there  is  a certain  amount  of  duplication  and 
Sishebogema  (lake  with  many  bays)  or  Pokegama  (side  or  branch  lake) 
may  be  cited  as  examples.  It  is  too  bad  that  these  names  have  not  been 
retained  to  a greater  extent,  but  certain  of  the  English  names  like 
Razorback,  Crawling  Stone,  Lost  Canoe,  Tenderfoot  or  Fishtrap  are  not 


* Birge,  E.  A.  and  Juday,  C.  The  inland  lakes  of  Wisconsin.  Bull.  27:  Wis. 
Geol.  & Nat.  Hist.  Survey.  (Sci.  Ser.  9).  pp.  1-137.  1914. 


12 


INTRODUCTION  ^ 


without  interest.  This  is  not  the  place,  however,  for  the  legends  on 
the  origin  of  these  peculiar  names  nor  for  a discussion  of  the  occurrence 
of  several  French  names  in  the  list.  In  order  to  avoid  misunder- 
standing the  town  and  range  in  which  the  lake  occurs  is  given.  When 
more  than  one  lake  with  the  same  name  has  been  visited,  a serial  num- 
ber has  been  added  and  both  the  lake  name  and  serial  number  are  used 
in  giving  stations  for  the  various  algae. 


INTRODUCTION 


13 


Table  2.  — 'Table  giving  available  data  on  location  and  size  of  lakes  visited  during  the 
course  of  this  investigation.  'The  first  column  refers  to  the  page  on  which  a mop 
of  the  lake  may  be  found  in  Birge  and  Juday,  The  inland  lakes  of  Wisconsin,  the 
hydrography  and  morphometry.  Bull.  27.  Wis.  Geol.  and  Nat.  Hist.  Survey. 


Papre 

map- 

ped 

Lake 

County 

Town 

Ranffe 

Lenffth 

(Miles) 

Maxi- 

mum 

breadth 

(miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

Adelaide 

Vilas 

43N 

5E 

1 .47 

.32 

68.9 

45 . 0 

Rusk 

34  N 

1 

8W  i 

1.06 

.30 

1?0 

Polk 

34N 

1 

17W 

3.00 

l.OO 

18.0 

1,785.6 

Bass  0) 

Vilas 

40N 

HE 

.50 

.24 

Bass  (2) 

Vilas 

42N 

GE 

.93 

irr. 

40N 

14W 

Bear  (1) 

34N 

14W 

.45 

.40 

Bear  (2) 

Polk 

33N 

17W 

.88 

.59 

120 

Bear  (3) ■. 

36N 

12W 

4.50 

1.00 

Washburn. 

Bear  Trap 

Polk 

.33N 

17W 

1.05 

.48 

104 

Beasley 

Waupaca  .... 

21N 

HE 

.25 

.10 

51.2 

13.5 

Beavei*  (1) 

Vilas 

44N 

5E 

,44 

• 25 

40 

Beaver  (2) 

Waukesha  ... 

8N 

18E 

MO 

.44 

49.0 

305.4 

120 

Beaverdam 

Barron 

33N 

14W 

3.80 

.75 

91.9 

1,267.2 

36N 

13W 

Bettine 

Vilas 

43N 

7E 

.75 

.56 

120 

Biff 

Polk 

32N 

18W 

.80 

.65 

33N 

120 

Biff  Butternut 

Polk 

36N 

17W 

1.20 

.60 

21.3 

384.0 

120 

Biff  McKenzie 

• Burnett 

40N 

14W 

2.25 

1.05 

116 

Biff  St,  Germain 

Vilas 

40N 

8E 

2.62 

1.25 

118 

Birch  (1) 

Vilas 

43N 

5E 

1.50 

.74 

120 

Birch  (2) 

Washburn .. . 

37N 

low 

.90 

.70 

57.4 

243.2 

120 

Birch  Island 

Burnett 

40N 

14W 

2.10 

irr. 

Blake 

Polk 

35N 

16W 

1.90 

irr. 

Bloom 

Burnett 

37N 

18W 

Blue  Gill 

Vilas 

43N 

7E 

.12 

.09 

120 

Bone 

Polk 

35N 

16W 

4.80 

1.00 

49.2 

2,054.4 

36N 

118 

Boulder 

Vilas 

42N 

7E 

2.25 

1.20 

19.7 

614.4 

74 

Browns 

Racine 

2N 

19E 

1.25 

.75 

23.0 

390.4 

3N 

Bullhead 

Vilas 

4CN 

6E 

.31 

.26 

IZ 

Camp 

Kenosha 

IN 

20E 

1.50 

1.00 

19.7 

256.0 

Canteen 

Vilas 

43N 

7E 

.31 

.17 

116 

Carroll 

Vilas 

SON 

7E 

1.30 

.47 

23.0 

288.0 

40N 

Carson  (see  Flora) 

14 


INTRODUCTION 


Table  2. — (Continued) 


Pa^e 

map- 

p<'.d 

Lake 

County 

Town 

Range 

Length 
V Miles) 

Maxi- 

mum 

breadth 

(miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

116 

Vilas 

SON 

lOE 

2.87 

irr. 

19.7 

902.4 

40N 

HE 

116 

Vilas 

38N 

6E 

2.25 

Avv. 

27.9 

008. 0 

75 

IN 

20E 

.72 

.3") 

Polk 

35N 

13W 

37N 

120 

38N 

9W 

6.40 

1.10 

120 

33N 

low 

3.25 

irr. 

120 

38N 

low 

3.84 

1.92 

39N 

Polk 

35N 

IGW 

. ^5 

.3G 

116 

Oneida 

SON 

7E 

2.10 

irr. 

82.0 

921.6 

116 

Vilas 

42N 

7E 

1.40 

1.12 

32.8 

672.0 

43N 

8E 

.69 

.36 

116 

Crab 

Vilas 

43N 

6E 

2.12 

1.35 

44.3 

1,318.4 

116 

Cranberry 

Vilas 

40N 

HE 

1.25 

.70 

11.5 

332.8 

116 

Crawl in»  Stone 

Vilas 

40N 

5E 

2.40 

1.65 

93.0 

1,600.0 

Rnrnet.t 

38N 

16W 

1.44 

.44 

II 

P.n  rlis 

Oneida 

SON 

6E 

.76 

.25 

120 

DpAr 

Polk 

S4N 

17W 

2.80 

.70 

39.4 

806.4 

18W 

70 

Delavan 

Walworth 

2N 

16E 

3.75 

1.10 

56.7 

1,813.2 

J')p<  Mninp.s 

Itnrnett 

41N 

14  W 

1.00 

.30 

30,  32 

Devils  (1) 

Pauk 

IIN 

6E 

1.25 

.61 

43.2 

360.8 

120 

J vj  1 

Ua  iTon  

36N 

HW 

1.60 

.40 

J i ] s 

Vilas 

4SN 

8E 

.44 

.26 

nininrmd 

Polk 

37N 

17W 

.60 

.60 

120 

' I'inpk  . 

Ba.rvnn 

SON 

13W 

.50 

.30 



Rn.rT'on 

86N 

13W 

.60 

.25 

J>nTihflnn  

Bn  I'tiplt 

38N 

17W 

ma  nn 

Rn  iTief  t 

38N 

17W 

74 

Eaffle 

Kacine 

SN 

20E 

1.31 

1.00 

13.1 

486.4 

120 

‘Fla.'it.  

Polk 

33N 

18W 

.74 

.52 

75 

Elizabeth 

Kenosha 

IN 

19E 

2.62 

.87 

26.2 

800.0 

116 

Eenp.e  

Vilas 

40N 

5E 

3.25 

2.10 

93.0 

3,492.0 

120 

Fish 

Burnett 

40N 

14W 

1.30 

.55 

116 

Fishtrap 

Vilas 

42N 

7E 

1.50 

.62 

29.5 

326.4 

116 

Flora  

Vilas 

43N 

7E 

1.31 

irr. 

Listed  as  Clear  Lake  by  Birtre  and  Juday. 


INTRODVCTIOIi 


15 


Table  2 (Continued) 


Page 

map- 

ped 

Lake 

County 

Town 

Range 

Length 

(Miles) 

Maxi- 

mum 

breadth 

(Miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

116 

Found 

Vilas 

inxT 

8E 

1.06 

.69 

52 

Fowler 

Waukesha ... 

8N 

17E 

.94 

.44 

50.0 

W 83.5 

66 

Geneva 

Walworth 

IN 

16E 

7.50 

2.00 

142.0 

5,451.3 

2N 

17E 

George 

Vilas 

44N 

5E 

.56 

.33 

120 

Granite 

Barron 

36N 

13W 

1.60 

.30 

Grassy 

Vilas 

42N 

7E 

1.31 

.64 

92 

Green  (1) 

Green  Lake. . 

15N 

12E 

7.40 

2.00 

237.0 

7,342.4 

16N 

1.SE 

76 

Green  (2) 

Walworth 

4N 

16E 

1.09 

.66 

56.8 

277.9 

120 

Grindstone 

Sawyer 

40N 

8W 

3.40 

2.10 

47.6 

3,462.4 

120 

Half  Moon 

Polk 

35N 

9W 

17W 

1.77 

.50 

116 

Harris 

Vilas 

44N 

5E 

1.51 

irr. 

Helen  (1) 

Vilas 

40N 

HE 

.58 

.14 

Helen  (2) 

Vilas 

44N 

5E 

.47 

.20 

116 

High 

Vilas 

42N 

7E 

2.00 

1.00 

31.2 

761.6 

43N 

8E 

Hill 

Oneida 

39N 

6E 

.18 

.14 

Hillman 

Barron 

34N 

14W 

.60 

.25 

75 

Hooker 

Kcnosiha. 

IN 

20E 

.75 

.37 

23.0 

64.0 

120 

Horse 

Polk 

33N 

18W 

1.22 

.40 

120 

Horseshoe®  (1 ) 

Polk 

34N 

15W 

2. .50 

1.00 

59.0 

800.0 

120 

Horseshoe  (2) 

Polk 

33N 

17W 

.80 

.62 

Howey 

Polk 

34N 

17W 

.25 

.20 

120 

Island 

Busk 

33N 

8W 

1.75 

.65 

47.6 

435.2 

118 

Jag 

Vilas 

42N 

6E 

1.00 

irr. 

Jennie 

Vilas 

43N 

6E 

.44 

.34 

Jones 

Vilas 

43N 

8E 

.58 

.21 

116 

Kawaguesaga 

Oneida 

39N 

6E 

4.25 

irr. 

55.8 

2067 . 2 

26 

Kegonsa 

T)a,ne 

6N 

7E 

lOE 

3.00 

2.25 

31.4 

3,145.2 

HE 

Kimball 

Washburn . . . 

42N 

13W 

1.68 

.80 

Kitten 

Vilas 

43N 

7E 

.34 

.19 

120 

Lac  Court  Oreilles.. . 

Sawyer 

39N 

8W 

5.65 

1.90 

67.2 

5 248.0 

40N 

9W 

116 

Lac  du  Flambeau 

Vilas 

40N 

4E 

2.00 

irr. 

49.2 

1,280,0 

5E 

52 

Lac  la  Belle 

Waukesha  ... 

8N 

17E 

2.70 

1.12 

46.4 

1,137.5 

116 

Laura 

Vilas 

41N 

8E 

1.50 

.90 

39.4 

640.0 

Lake  of  the  Woods. . 

Burnett 

38N 

17W 

’ Listed  as  Big:  Horseshoe  by  Birge  and  Juday. 


16 


INTRODUCTION 


Table  2 — (Continued) 


Page 

map- 

ped 

Lake 

County 

Townj 

Range 

Length 

(Miles) 

Maxi- 

mum 

breadth 

(Miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

Lily 

41N 

14W 

Lindy 

Burnett 

40N 

14W 

Little  Bass  (1) 

Vilas 

42N 

6E 

.28 

.19 

Polk 

34N 

17  W' 

Little  Bear 

Vilas 

43N 

6E 

.69 

.44 

Polk 

36N 

17W 

.60 

.35 

Little  Crooked 

Vilas 

42N 

6E 

1.06 

irr. 

38N 

17W 

,45 

.30 

T.ittle  Rice  (1) 

33N 

8W 

.70 

.40 

118 

Little  Rice  (2i 

Vilas 

42N 

7E 

.76 

.38 

120 

38N 

18W 

.82 

.48 

T.rmg  n 1 

Burnett 

41N 

14W 

1.85 

.35 

120 

Long  (2)., 

Polk 

34N 

17W 

1.70 

.55 

24.6 

384.0 

liOng  CSl 

Vilas 

40N 

1 5E 

1.40 

.60 

55.8 

448.0 

104 

Long  (4) 

Waupaca  . . . . 

21N 

HE 

.94 

.36 

77.7 

108.4 

TiOmi 

Barron 

34N 

1 14W 

1.00 

.45 

116 

T .osjt',  

Vilas 

40N 

8E 

1.69 

.86 

118 

T.nst  Canoe 

Vilas 

42N 

7E 

1.25 

.38 

41.0 

204.8 

120 

T,r>veless 

Polk 

34N 

17W 

1.09 

.32 

21.3 

153.6 

T.ynv 

Vilas 

43N 

i 7E 

.75 

.66 

1 

1 

! Vilas 

44N 

I r>E 

.37 

.19 

104 

Marion j 

Marl ! 

Waupaca 

21N 

HE 

.51 

.19 

60.6 

21.3 

75 

Mary 

Kenosha 

IN 

19E 

1.20 

.70 

26.2 

275.2 

12 

Mendota 1 

1 Dane. 

7N 

9E 

5.90 

4.60 

84.0 

9,729.8 

8N 

Mercer 

Oneida 

39N 

5E 

1.30 

.69 

Mernnt  . . 

j Rnrnet.t 

40N 

14W 

i M etfl 

Vilas 

40N 

HE 

.64 

.26 

76 

Middle 

Walworth. . . . 

4N 

16E 

1.60 

.45 

50.0 

284.0 

120 

Middle  McKenzie  ® . . 

Rn  rnet.t. 

40N 

14W 

1.10 

.90 

78 

Mill 

Walworth  — 

• 4N 

16E 

.75 

.49 

50.0 

296.4 

20 

Monona 

Dane 

7N 

9E 

4.16 

2.40 

74.0 

3,482.7 

lOE 

Mild  (11  . . . 

Polk 

34N 

17W 

.66 

.28 

Mnd  (21 

Vilas 

40N 

5E 

.81 

.56 

114 

Mud  (8) 

Vilas 

.89N 

7E 

.87 

.36 

* Listed  as  McKenzie  lakes. 


INTRODUCTION 


17 


Table  2 — (Continued) 


1 

1 

1 Lake 

County 

1 

! Town 

1 

Rang’e 

Length 

(Miles) 

Maxi- 

mum 

breadth 

(Miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

104 

Mud  (4) 

Waupaca 

21N 

HE 

.13 

.06 

32.0 

i 

i 9.7 

38N 

17  W 

1.68 

1.10 

i 

116 

Vilas 

41N 

7E 

i 1.93 

irr . 

1 

1 

^20 

42N 

13W 

1 2.00 

1.25 

54 

Naerawicka 

Waukesha  .. . 

7N 

18E 

I 2.75 

1.12 

94.4 

917.6 

54 

Nashotah  (Upper).. . 

Waukesha  .. . 

7N 

17E 

.81 

.40 

57.2 

1.36.7 

54 

Nashotah  (Lower) . . 

Waukesha  .. . 

7N 

17E 

.79 

.25 

46.2 

100.3 

Nell 

Vilas 

44N 

5E 

1 .46 

.15 

54 

Nemahbin  (Upper).. 

Waukesha .. . 

7N 

17E 

1.05 

.56 

62.0 

271.1 

54 

Nemahbin  (Lower). . 

Waukesha .. . 

7N 

17E 

.93 

.60 

35.2 

265.5 

41N 

14W 

116 

Vilas 

44N 

5E 

1.00 

.69 

North  Twin 

Polk 

33N 

16W 

.92 

.30 

Number  One 

Sawyer 

37N 

9W' 

.25 

.18 

Oak 

Burnett 

40N 

14W 

.70 

• 45 

46 

Oconomowoc 

Waukesha. . . 

7N 

17E 

1.75 

.83 

62.6 

631.3 

46 

Okauchee 

Waukesha. . . 

8N 

17E 

2.37 

1.80 

94.0 

1,0.57.0 

18E 

Old  Taylors 

Waupaca  .... 

22N 

HE 

104 

Otter 

Waupaca 

22N 

HE 

.40 

.08 

40.0 

14.5 

120 

Owen 

Bavfield  .... 

44N 

7W 

6.25 

irr. 

88.6 

2.032.0 

43N 

75 

Paddock 

Keno.sha, 

IN 

20E 

.62 

.37 

31.0 

9.5 

116 

Palmer 

Vilas 

43N 

8E 

1.75 

1.25 

14.8 

614.4 

116 

Pardee 

Vilas 

44N 

4E 

.94  1 

.87 

63 

Pewaukee 

Waukesha  .. . 

7N 

18E 

4.50 

1.20 

45.0 

2,298.0 

19E 

Pike 

Polk 

33N 

16W 

1.18 

.30 

40 

Pine  (1) 

Waukesha... . 

8N 

18E 

2.30 

1.05 

90.0 

755.7 

Pine  (2) 

Polk 

33N 

17W^ 

.66 

.28 

Pine  Tree 

Polk 

32N 

16W 

.92 

irr. 

116 

Plum 

Vilas 

41N 

7E 

4.20 

1.25 

50.8 

1,088.0 

8E 

120 

Pokegrama  (1) 

Washburn 

42N 

12W 

2.40 

.60 

23.0 

505.6 

116 

Pokegrama  (2) 

Vilas 

40N 

5E 

3.25 

1.90 

42.6 

1,216.0 

41N 

120 

Poke^ama  (3) 

Barron 

33N 

low 

3.50 

.70 

Poor  Farm 

Polk 

33N 

ICW' 

104 

Pope 

Wa.npac.Ji  .... 

21N 

HE 

.22 

.11 

40.6 

16.2 

120 

Poplar 

Polk 

33N 

18W 

.72 

.38 

9 


18 


INTRODUCTION 


Tablb  2. — (Continued) 


Page 

map- 

ped 

Lake 

County 

Town 

Range 

Length 

(Miles) 

Maxi- 

mum 

breadth 

(Miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

8 

Poygan 

Waushara  ... 

19N 

13E 

7.70 

3.50 

10.8 

10,992.2 

120 

Prairie 

33N 

IIW 

6.50 

.70 

34N 

104 

Rainbow  (1) 

22N 

HE 

.62 

.55 

95.1 

137.5 

116 

Rainbow  (2) 

Vilas 

44N 

5E 

.63 

.44 

116 

Razorback 

Vilas 

41N 

8E 

1.10 

.90 

31.1 

352.0 

Red  Bass 

Vilas 

43N 

7E 

.40 

.13 

Reserve 

39N 

8W 

1.00 

.55 

Rice  (1) 

35N 

IIW 

2.75 

.60 

Rice  (2) 

Vilas 

42N 

6E 

.45 

.30 

Rock 

Vilas 

44N 

5E 

1.12 

.37 

Roonev  

40N 

14  W 

Rose 

Vilas 

40N 

7E 

1.14 

.25 

Round  O) 

Vilas 

43N 

6E 

.62 

.40 

Round  (2) 

Polk 

33N 

18W 

.58 

.41 

Round  (3) 

Polk 

32N 

17W 

.26 

.20 

104 

Round  (4) 

Waupaca 

22N 

HE 

.55 

.35 

66.6 

106.2 

Rozen 

Vilas 

40N 

7E 

.68 

.50 

116 

Rudolnh 

Vilas 

43N 

7E 

.52 

.22 

120 

St.  Croix 

Douglas 

45N 

IIW 

4.00 

.55 

19.7 

1,030.4 

12W 

Sand  (1) 

Burnett, 

38N 

16W 

120 

Sand  (2) 

Burnett 

40N 

15W 

1.70 

1.45 

120 

Sand  (3) 

Polk 

33N 

18W 

1.22 

.45 

116 

Sand<  (4) 

Vilas 

42N 

7E 

1.65 

.87 

67.2 

793.6 

Sanford  

Vilas 

43N 

6E 

.77 

.40 

120 

Shell 

Washburn. . . 

37N 

12W 

3.25 

2.50 

49.2 

3,200.0 

38N 

13W 

120 

Silver  HI 

Ba.rron  

36N 

13W 

75 

Silver  (2) 

Kenosha 

IN 

20E 

1.25 

.87 

42.6 

582.0 

58 

Silver  (3) 

Waukesha... . 

7N 

17E 

.97 

.56 

44.0 

231.9 

Sishebocema 

Vilas 

39N 

5E 

2.50 

irr. 

40N 

58 

Soft 

Waukesha... . 

7N 

17E 

.32 

.20 

Speese 

Oneida 

39N 

5E 

.32 

.31 

116 

SQuirrel 

Oneida. 

39N 

5E 

3.75 

1.00 

33.8 

1,568.0 

Sonl.h  Crab 

Vilas 

43N 

6E 

.68 

.20 

120 

Spirit 

Burnett 

37N 

18W 

1.70 

1.00 

24.6 

640.0 

116 

Star 

Vilas 

41N 

8E 

2.12 

1.60 

26.2 

1,152.0 

* Listed  as  White  Sand  Lake  by  Birg-e  and  Juday. 


INTRODUCTION 


19 


Table  2 --(Continued) 


Page 

map- 

ped 

Lake 

County 

Town 

Range 

Length 

(Miles) 

Maxi- 

mum 

breadth 

(Miles) 

Maxi- 

mum 

depth 

(Feet) 

Area 

(Acres) 

Vilas 

42N 

6E 

.44 

.28 

39N 

5E 

. 75 

.37 

Vilas 

4SN 

5E 

.56 

.40 

Tank 

ON 

6E 

.24 

.08 

104 

22N 

HE 

.45 

.31 

55.7 

51.2 

116 

43N 

8E 

1.60 

1.50 

27.9 

646.4 

Tied  Canoe  ® 

Travis 

Polk 

33N 

17W 

116 

Trout 

Vilas  

41N 

6E 

4.50 

2.40 

115.0 

4,160.0 

42N 

7E 

116 

Turtle  (North) 

Vilas 

43N 

5E 

1.25 

.80 

47.6 

640.0 

116 

Turtle  (South) 

Vilas 

43N 

5E 

2.25 

.63 

43.0 

793.6 

120 

Turtle  (Lower) 

Barron 

34N 

14W 

1.50 

.45 

120 

Turtle  (Upper) 

Barron 

34N 

14W 

2.30 

.40 

23.0 

480.0 

120 

Vermilion 

Barron 

3f)N 

13W 

1.70 

1.20 

120 

WapagossetU 

Polk 

33N 

ICW 

3.50 

1.20 

27.9 

1,452.8 

17W 

24 

Waubesa 

Dane 

6N 

lOE 

4.20 

1.40 

36.6 

2,034.4 

7N 

White  Ash 

Polk 

34N 

low 

1.77 

.40 

120 

Whitefish 

Sa.wypr 

39N 

9W 

2.60 

. 65 

73.8 

896.0 

116 

White  Sand 

Vilas 

41N 

5E 

2.75 

1.00 

Whitney 

Vila.s 

42N 

6E 

.56 

.45 

116 

Wildcat 

Vilas 

43N 

7E 

.87 

.60 

120 

Wild  Goose 

Polk 

34N 

17W 

.95 

.64 

14.8 

256.0 

92 

Winnebago 

15N 

17E 

28.00 

10.40 

21.0 

137,708.0 

20N 

116 

Wolf 

Vilas 

42N 

7E 

1.21 

.84 

104 

Youngs 

Waupaca 

21N 

HE 

.09 

.07 

11.6 

3.0 

®See  Lost  Canoe. 

•Listed  as  Sucker  Lake  by  Birge  and  Juday. 


KEY  TO  THE  GENEEA  BASED  UPON  THE 
VEGETATIVE  CHAKACTERS. 


1.  (35)  Celoring  matter  not  restricted  to  definite  plastids 

Class  Myxophyceae 

2.  (22)  Cells  solitary  or  in  colonies,  never  in  filaments 

Order  Coccogoneales 

3.  (12)  Cells  solitary  or  in  colonies  that  never  contain  more  than 

a few  cells 

4.  ( 7)  Cells  spherical  or  hemispherical 

5.  ( 6)  Cells  without  a definite  arrangement Chroococcus  p. 

6.  ( 5)  Cells  in  a flat  plate Merismopedia  p. 

7.  ( 4)  Cells  longer  than  they  are  broad 

8.  (11)  Individual  cells  not  enclosed  by  a special  gelatinous  vesicle 

9.  (10)  Ends  of  cells  rounded Rhabdoderma  p. 

10.  ( 9)  Ends  of  cells  pointed Dactylococcopsis  p. 

11.  ( 8)  Individual  cells  or  groups  of  cells  enclosed  by  a gelatinous 

vesicle  Gloeothece  p. 

12.  ( 3)  Cells  in  colonies  that  contain  many  cells  when  mature 

13.  ( 18)  Cellular  arrangement  within  colony  definite  

14.  ( 15)  Cells  forming  a flat  plate Merismopedia  p. 

15.  ( 14)  Cells  forming  a hollow  sphere  one  cell  in  thickness 

16.  ( 17)  Center  of  colony  with  radiating  gelatinous  strands 

Gomphosphaeria  p. 

17.  ( 16)  Center  of  colony  without  radiating  gelatinous  strands 

Coelosphaerium  p. 


18.  ( 21)  Cells  spherical  

1’9.  ( 20)  Cells  densely  aggregated Microcystis  p. 

20.  ( 19)  Cells  some  distance  from  one  another Aphanocapsa  p. 

21.  ( 18)  Cells  longer  than  they  are  broad Aphanothece  p. 


22.  ( 2)  Cells  in  simple  or  branched  filaments.  .Order  Hormogoneales 

23.  ( 30)  Trichomes  without  heterocysts Family  Oscillatoriaceae 

24.  ( 29)  Trichomes  solitary  or  in  flocculent  readily  dissociating 

masses 

25.  ( 26)  Trichomes  containing  but  one  spirally  twisted  cell 

Spirulina  p. 

26.  ( 25)  Trichomes  containing  more  than  one  cell 

27.  ( 28)  Sheaths  of  filament  firm,  generally  projecting  beyond  the 

trichome  Lyngbya  p. 

28.  ( 27)  Sheath  delicate  or  lacking,  not  projecting  beyond  the  tri- 

chome   Osclllatorla  p. 

29.  ( 24)  Trichomes  laterally  united  to  form  free-floating  bundles 

which  do  not  dissociate  readily Trichodesmium  p. 

30.  ( 23)  Trichomes  with  heterocysts 


2 

3 

4 

5 

27 

31 

8 

9 

46 

47 

15 

13 

14 

31 

16 

36 

33 

19 

38 

41 

43 

23 

24 

25 

,49 

27 

. 52 

.50 

,54 

31 


22 


WISCONSIN  PHYTOPLANKTON 


31.  ( 34)  Trichomes  not  attenuated Family  Nostocaceae  32 

32.  ( 33)  Filaments  solitary  or  interwoven  to  form  flocculent  masses 

of  small  size Anabaena 

33.  ( 32)  Filaments  laterally  joined  to  form  small  plate-like  colonies 

of  macroscopic  size Aphanizomenon 

Trichomes  attenuated  to  a hair-like  point Gloeotrichia 

Coloring  matter  in  definite  chromatophores 

Chromoplasts  golden  brown  in  color 

Wall  heavily  impregnated  with  silica  and  definitely  marked 

with  grooves  or  rows  of  dots Bacillarieae  (see  part  2). 

Wall  not  heavily  impregnated  with  silica 

Class  Phaeophyceae 

Cells  generally  motile,  rarely  forming  palmella  or  rhizopo- 

dial  stages Division  Euchrysomonadinae 

Cells  with  one  flagellum Order  Chromulinales 

Cells  naked Chrysamoeba 

Cells  with  a differentiated  periplast 

Family  Mallomonadaceae 

Cells  solitary Mallomonas 

Cells  in  colonies Chrysosphaerella 

Cells  with  two  flagella 

Flagella  of  equal  length Synura 

Flagella  of  unequal  length Order  Ochromonadales 

Cells  in  a definite  receptacle Family  Dinobryaceae 

Receptacles  homogeneous,  without  growth  rings.  .Dinobryon 

Receptacles  with  successive  growth  rings Hyalobryon 

Cells  never  in  a definite  receptacle Uroglenopsis 

( 39)  Cells  usually  immobile,  rarely  motile 

( 54)  Cells  spherical  to  ovoid,  embedded  in  a gelatinous  mass 

Phaeococcus 

54.  ( 53)  Cells  with  pseudopodial  processes 

Division  Rhlzochrysidinae 

Cells  solitary  or  in  irregular  colonies Rhizochrysis 

Cells  in  a linear  series Chrysidastrum 

Chromoplast  grass-green  or  yellowish-green  in  color 

Chromoplast  yellowish-green,  with  oil  not  starch  the  assimi- 
lation product  Class  Heterokonteae 

Vegetative  cells  motile Chlorochromonas 

Vegetative  cells  immobile  

Cells  solitary  or  in  colonies,  never  in  filaments 

Order  Heterococcales 

Cells  epiphytic  Peroniella 

Cells  free-floating  

Length  of  cells  several  times  the  diameter Ophiocytium 

Length  of  cells  less  than  twice  the  diameter 

Cells  irregularly  distributed  throughout  an  ovoid,  gelatinous 
envelope  Chlorobotrys 

67.  ( C6)  Cells  arranged  about  a common  center  and  enclosed  by  an 

irregular,  gelatinous  envelope Botryococcus 

68.  ( 61)  Cells  united  to  form  simple  filaments Tribonema 

69.  ( 58)  Chloroplast  grass-green,  generally  with  pyrenoids  and  starch 

Class  Chlorophyceae  70 


34. 

35. 

36. 

37. 

38. 

39. 

40. 

41. 

42. 

43. 

44. 

45. 

46. 

47. 

48. 

49. 

50. 

51. 

52. 

53. 


55. 

56. 

57. 

58. 

59. 

60. 
61. 

62. 

63. 

64. 

65. 

66. 


( 31) 
( 1) 
( 57) 
( 38) 

( 37) 

( 52) 

( 45) 
( 42) 
( 41) 

( 44) 
( 43) 
( 40) 
( 47) 

( 46) 
( 51) 
( 50) 

( 49) 
( 48) 
9) 


( 56) 
( 55) 
( 36) 
( 69) 

( 60) 
( 59) 
{ 68) 

( 63) 
( 62) 
( 65) 
( 64) 
( 67) 


p.  55 

p.  61 

p.  63 

36 

37 


39 

40 

41 
p.  67 

43 
p.  67 
p.  69 
46 
p.  70 

48 

49 
p.  72 
p.  75 
p.  71 

53 

p.  76 

55 
p.  77 
p.  78 

58 

59 

p.  80 
61 

62 
p.  81 

64 

p.  85 
66 

p.  82 

p.  33 
p.  87 


70. 

( 71) 

71. 

( 70) 

72. 

( 85) 

73. 

( 84) 

74. 

( 75) 

75. 

( 74) 

76. 

( 77) 

77. 

( 76) 

78. 

( 79) 

79. 

( 78) 

80. 

( 83) 

81. 

( 82) 

82. 

( 81) 

83. 

( 80) 

84. 

( 73) 

85. 

( 72) 

86. 

(183) 

87. 

(122) 

88. 

(121) 

89. 

( 92) 

90. 

( 91) 

81. 

( 90) 

92. 

( 89) 

93. 

(116) 

94. 

(109:) 

95. 

(102) 

96. 

( 99) 

■97. 

( 98) 

98. 

( 97) 

99. 

( 96) 

100. 

(101) 

101. 

(100) 

102. 

( 95) 

103. 

(108) 

104. 

(107) 

105. 

(106) 

106. 

(105) 

107. 

(104) 

108. 

(103) 

109. 

( 94) 

110. 

(111) 

111. 

(110) 

112. 

(113) 

113. 

(112) 

WISCONSIN  PHYTOPLANKTON 


23 


Cells  solitary  or  in  families,  divided  into  two  symmetrical 
halves  with  a chloroplast  in  each  half.  Median  region 
generally  constricted . . Family  Desmidiaceae  (See  Part  2 ) 
Cells  not  divided  into  two  symmetrical  halves  and  without 

median  constrictions  

Cilia  normally  present  in  vegetative  cells.  .Order  Volvocales 

Anterior  end  of  cells  with  two  cilia 

Cells  solitary  Chlamydomonas 

Cells  in  colonies  Family  Volvocaceae 

Colony  a flat  plate  Gonium 

Colony  a hollow  sphere 

Cells  mutually  compressed  Pandorina 

Cells  some  distance  from  one  another  

Colony  with  not  more  than  256  cells 

Asexual  reproduction  by  division  of  all  cells  to  form  daugh- 
ter colonies  Eudorina 

Asexual  reproduction  by  division  of  certain  cells  to  form 

daughter  colonies  Pleodorina 

Colony  generally  containing  many  cells Volvox 

Anterior  end  of  cells  with  four  cilia Carteria 

Cilia  not  present  in  vegetative  cells  

Cells  solitary  or  in  colonies,  never  in  simple  or  branched 

filaments Order  Protococcales 

Cells  solitary  

Cells  free-floating  

Cell  shape  angular  

Angles  simple  or  with  spines,  never  with  long  setae 

Tetraedron 

Angles  with  tufts  of  long  setae Polyedriopsis 

Cells  spherical,  ovoid,  or  elongate 

Length  of  cells  not  more  than  three  times  the  diameter. . . . 

Cells  spherical  

Cell  w^all  smooth  

Cells  embedded  in  a gelatinous  sheath 

Gelatinous  sheath  lamellated Gloeocystis 

Gelatinous  sheath  not  lamellated Planktosphaeria 

Cells  not  embedded  in  a gelatinous  sheath 

Wall  lamellated  Gloeotaenium 

Wall  not  lamellated  Chlorella 

Wall  sculptured,  denticulate,  or  with  long  spines  or  setae.. 

Setae  or  long  spines  covering  the  wall 

Wall  with  setae 

Setae  the  same  thickness  throughout,  or  gradually'  taper- 
ing   Golenkinia 

Setae  visibly  thickened  in  the  lower  third. . Acanthosphaeria 

Walls  with  long  spines Echinosphaerella 

Denticulations  or  ridges  covering  the  walls Trochiscia 

Cells  ovoid  to  reniform  

Cells  reniform  Nephrocytium 

Cells  ovoid  

Walls  without  setae  or  spines Oocystis 

Walls  with  spines  or  setae 


72 

73 

74 
p.  90 

76 
p.  94 
78 
p.  95 
80 
81 

p.  95 

p.  96 
p.  97 
p.  92 
86 

87 

88 

89 

90 


p.  115 
p.  124 

93 

94 

95 

96 

97 

p.  100 

p.  103 
100 
p.  115 

p.  108 

103 

104 

105 

p.  127 

p.  128 
p.  128 
108 
110 
p.  114 
112 
p.  110 

114 


24  WISCONSIN  PHYTOPLANKTON 


114.  (116)  Setae  somewhat  tapering Lagerheimia  p. 

115.  (114)  Setae  not  tapering Franceia  p. 

116.  ( 93)  LfCngth  of  cells  several  times  the  diameter 

117.  (118)  Ends  of  cells  produced  into  setae Schroederia  p. 

118.  (117)  Ends  of  cells  not  produced  into  setae 

119.  (120)  Chloroplast  with  an  axial  row  of  pyrenoids Closteriopsis  p. 

120.  (119)  Chloroplast  without  or  with  one  pyrenoid. . Ankistrodesmus  p. 

121.  ( 88)  Cells  epiphytic  or  epizootic Characium  p. 

122.  ( 87)  Cells  in  colonies 


123.  (142)  Colonies  enclosed  by  a conspicuous  gelatinous  sheath 

124.  (125)  Cells  connected  by  branching  remains  of  old  cell  walls 

Dictyosphaerium  p. 

125.  (124)  Cells  not  connected  by  branching  remains  of  old  cell  walls. . 

126.  (137)  Cells  spherical  to  ovoid  or  reniform 

127.  (136)  Chloroplast  cup  to  disc-shaped  and  parietal 


128.  (129)  Cells  with  pseudocilia Tetraspora  p. 

129.  (128)  Cells  without  pseudocilia - 

130.  (131)  Colonies  never  containing  more  than  eight  cells.  .Gloeocystis  p. 

131.  (130)  Colonies  always  with  at  least  eight  cells 

132.  (133)  Cells  ovoid  to  reniform Gloeocystopsis  p. 

j33.  (132)  Cells  spherical  

134.  (136)  Chloroplasts  of  old  cells  cup-shaped.. Sphaerocystis  p. 

io5.  (134)  Chloroplasts  of  old  cells  disciform Planktosphaeria  p. 

136.  (127)  Chloroplasts  star-shaped  and  central Asterococcus  p. 

1S7.  (126)  Cells  elongate  

138.  (141)  Cells  straight 

139.  (140)  Colonies  with  cells  in  groups  of  two Elaktothrix  p. 

140.  (139)  Colonies  with  cells  in  groups  of  2-4-8 Quadrigula  p. 

141.  (138)  Cells  curved  Kirchneriella  p. 

112.  (123)  Cells  not  enclosed  by  a gelatinous  sheath 

148.  (156)  Colonies  always  forming  a flat  plate 


144.  (155)  Number  of  cells,  except  in  rare  cases,  greater  than  two 

145.  (152)  Cells  quadrately  arranged 

146.  (147)  Quadrate  arrangement  apparent  in  end  view  of  colony 

Tetradesmus  p. 

147.  (146)  Quadrate  arrangement  apparent  in  front  view  of  colony 


148.  (149)  Cells  without  setae  or  spines Crucigenia  p. 

149.  (148)  Cells  with  spines  or  setae 

150.  (151)  Long  setae  or  spines  on  outer  face  of  cells. . . .Micractinium  p. 

151.  (150)  Short  spines  on  outer  face  of  cells Tetrastrum  p. 

152.  (145)  Cells  not  quadrately  arranged  

153.  (154)  Colony  a fiat  circular  or  oval  disc Pediastrum  p. 

154.  (153)  Colony  a single  or  double  row  of  cells Scenedesmus  p. 

155.  (144)  Number  of  cells  in  colony  always  two Euastropsis  p. 

156.  (143)  Colony  not  forming  a flat  plate  

157.  (166)  Colony  enclosed  by  old  cell  wall 


158.  (165)  Wall  enclosing  colony  greatly  expanded  and  homogeneous.. 


159.  (162)  Wall  with  spines  or  setae 

160.  (161)  Setae  somewhat  tapering Lagerheimia  p. 

161.  (160)  Setae  not  tapering Franceia  p. 

162.  (159)  Wall  without  spines  or  setae 

163.  (164)  Cells  ovoid  Obcystis  p. 


129 

,131 

117 

136 

119 

,136 

,134 

175 

123 

124 

, 104 

126 

127 

128 

102 

130 

100 

132 

102 

134 

101 

103 

103 

138 

139 

139 

137 

140 

143 

144 

145 

146 

150 

148 

144 

150 

125 

149 

153 

166 

150 

174 

157 

168 

159 

160 

129 

131 

163 

110 


WISCONSIN  PHYTOPLANKTON 


25 


184.  (163)  Cells  ovoid  to  reniform Nephrocytium  p.  114 

165.  (158)  Wall  lamellated  but  not  expanded Gloeotaenium  p.  115 

166.  (157)  Colony  not  enclosed  by  old  cell  wall 167 

167.  (176)  Length  of  cell  not  more  than  twice  the  breadth 168 

168.  (171)  Remains  of  old  cell  walls  at  center  of  and  holding  colony 

together  169 

169.  (170)  Cells  spherical  Westella  p.  106 

170.  (169)  Cells  ovoid  to  reniform Dimorphococcus  p.  106 

171.  (168)  Colonies  without  remains  of  old  cell  wall  at  center 172 

172.  (173)  Outer  face  of  cells  with  long  setae Micractinium  p.  125 

173.  (172)  Outer  face  of  cells  with  short  spines  or  without  ornamenta- 

tion   174 

174.  (175)  Cells  without  spines  on  outer  face Coelastrum  p.  160 

175.  (174)  Cells  with  short  spines  on  outer  face Sorastrum  p.  162 

176.  (167)  Length  of  cells  several  times  the  breadth 177 

177.  (178)  Colony  forming  a closed  hollow  sac Hydrodictyon  p.  165 

178.  (177)  Colony  not  forming  a closed  hollow  sac 179 

179.  (180)  Cells  radiating  from  a common  center Actinastrum  p.  164 

380.  (179)  Cells  not  radiating  from  a common  center 181 

381.  (182)  Cells  straight  or  arcuate Ankistrodesmus  p.  134 

182.  (181)  Cells  markedly  curved Selenastrum  p.  132 

183.  ( 86)  Cells  in  simple  or  branched  filaments 184 

184.  (195)  Cells  with  one  to  eight  chloroplasts,  chloroplasts  never  re- 

ticulate   185 

185.  (192)  Chloroplasts  parietal  186 

186.  (191)  Chloroplasts  laminate  to  disciform 187 

187.  (188)  Cells  in  simple  filaments Ulothrix  p.  179 

188.  (187)  Cells  in  branching  filaments 189 

18'9.  (190)  Setae  confined  to  terminal  cells  or  lacking. ..  Stigeoclonium  p.  180 

190.  (189)  Setae  occurring  on  any  cell  of  filament Aphanochaete  p.  181 

191.  (186)  Chloroplast  a spiral  band Spirogyra  p.  185 

192.  (185)  Chloroplast  central  193 

193.  (194)  Chloroplast  an  axial  plate Mougeotia  p.  184 

194.  (193)  Chloroplasts  stellate  Zygnema  p.  184 

395.  (184)  Chloroplasts  numerous  or  united  to  form  a single  reticulate 

mass  Cladophora  p.  182 


26 


WISCONSIN  PHYTOPLANKTON 


Class  MYXOPHYCEAE. 

Cells  solitary,  in  colonies  of  definite  or  indefinite  shape,  or  in  fila- 
ments but  always  surrounded  by  a gelatinous  to  tough  envelope  which 
is  generally  hyaline  but  may  be  colored.  Plants  living  a free-fioating, 
sessile,  epiphytic  or  endophytic  existence.  Cell  shape  various;  spheri- 
cal, hemispherical,  ovoid,  bacilliform,  disciform  or  angular.  Cells  with 
the  coloring  matter  localized  at  the  periphery  but  not  in  definite,  visible 
ehromatophores.  Color  of  cells  typically  blue-green  but  at  times  grey, 
yellowish,  reddish,  brownish  or  nearly  grass-green.  The  color  variation 
being  due  to  different  amounts  of  the  three  component  pigments,  caro- 
tin, chlorophyll,  and  phycocyan;  the  latter  being  found  only  in  this 
class  of  plants.  Cells  containing  a single  nucleus  of  a primitive  type 
(the  central  body)  that  contains  linin  and  chromatin  but  is  without  a 
membrane  or  nucleole. 

Reproduction  always  asexual,  either  by  vegetative  division  of  cells; 
fragmentation  of  the  filaments  into  smaller  portions  (hormogones) 
which  may  move  a short  distance  by  spontaneous  movement  and  then 
come  to  rest;  or  by  special  non-motile  reproductive  bodies  (gonidia  and 
resting  spores) . 

KEY  TO  THE  ORDERS. 


Cells  solitary  or  in  colonies,  never  in  filaments Coccogoneau» 

Cells  in  simple  or  branched  filaments Hobmoqoneaubs 


Order  COCCOGONEALES. 

Cells  rarely  solitary,  generally  in  colonies  of  regular  or  irregular 
shape,  and  with  the  cells  definitely  or  indefinitely  arranged  within  a 
copious  gelatinous  envelope.  Colonies  living  a free-fioating,  sessile, 
epiphytic  or  endophytic  existence.  Cells  differentiated  into  a basal 
and  distal  portion  or  without  such  differentiation.  Cell  shape  various; 
spherical,  ovoid,  cylindrical,  acicular,  or  angular. 

Asexual  reproduction  by  vegetative  division  of  the  cells  or,  in  rare 
cases,  by  a division  of  the  cell  contents  into  non-motile  gonidia.  Rest- 
ing cells  and  sexual  reproduction  unknown. 

There  are  two  families  in  the  order  only  one  of  which,  the  Chroococ- 
caceae,  is  found  in  the  plankton. 


WISCONSIN  PHYTOPLANKTON 


27 


Family  CHROOCOCCACEAE. 

Cells  not  differentiated  into  an  apical  and  basal  portion ; rarely  soli- 
tary, generally  in  colonies  of  definite  or  indefinite  shape  and  always 
enclosed  by  a gelatinous  sheath.  Cell  shape  various,  and  cellular  ar- 
rangement within  the  colonial  envelope  definite  or  indefinite. 

Asexual  reproduction  by  vegetative  cell  division  and  the  fragmenta- 
tion of  the  colonies.  Gonidia  formation  occasionally  taking  place  in 
certain  genera. 

KEY  TO  THE  GENERA. 

Cells  solitary  or  in  colonies  that  never  contain  more  than  a few  cells. 

Cells  spherical  or  hemispherical ' Chboocxk'CUS 

Cells  longer  than  they  are  broad. 

Individual  cells  or  groups  of  cells  enclosed  by  a gelatinous 

vesicle  Gloeothece 

Individual  cells  or  groups  of  cells  without  vesicles. 

Ends  of  cells  rounded Rhabdodebma 

Binds  of  cells  pointed Dactylococcopsis 

Cells  always. in  colonies  that  contain  many  cells  when  mature. 

Cellular  arrangement  within  colony  definite. 

Cells  forming  a flat  plate Merismopedia 

Cells  forming  a hollow  sphere  one  cell  in  thickness. 

Center  of  colony  with  radiating  gelatinous  strands . Gomphosphaeria 

Center  of  colony  without  radiating  strands Coelosphaeriem: 

Cellular  arrangement  within  colony  indefinite. 

Cells  spherical. 

Cells  densely  aggregated  Microcystis 

Cells  some  distance  from  one  another Aphanocapsa 

Cells  longer  than  they  are  broad Aphanothbck 

CHROOCOCCUS  Nageli  1849. 

Cells  spherical,  usually  hemispherical  for  some  time  after  division; 
solitary  or  2-4r-8-16  or  more  united  in  colonies  enclosed  by  a hyaline 
or  colored,  homogeneous  or  lamellated  sheath;  free-floating,  sessile,  or 
epiphytic.  Individual  cells  of  colony  at  times  surrounded  by  a homo- 
geneous or  lamellated  sheath.  Cell  contents  grey,  grey-green,  blue- 
green,  olive-green,  yellowish,  orange,  reddish  or  violet  in  color;  homo- 
geneous or  granular. 

Reproduction  by  vegetative  division  of  cells  in  three  directions. 

KEY  TO  THE  SPECIES. 

Sheaths  enclosing  cells  homogeneous. 

Cells  solitary,  in  twos,  and  in  fours C.  Minutes 

Cells  in  colonies  of  4-8-16  or  more. 

Individual  cells  or  groups  of  cells  some  distance  from  one 

another  C.  Disperses 

Individual  cells  or  groups  of  cells  fairly  close  together . . C.  Limneticus 


28 


WISCONSIN  PHYTOPLANKTON 


Sheaths  enclosing  cells  distinctly  lamellated. 

Diameter  of  cell  and  sheath  not  exceeding  40  /x C.  Turgidus 

Diameter  of  cell  and  sheath  over  60  /x C.  Giganteus 


Chroococcus  Minutus  (Kiitzing)  Nageli.  PL  1,  Fig.  1. 

Gatt.  einz.  Algen  46.  1849. 

Protococcus  minutus  Kiitzing,  Tabulae  Phycol.  1:  pi.  5. 

Cells  spherical  or  hemispherical,  solitary  or  in  colonies  of  2-4  en- 
closed by  a wide,  spherical,  homogeneous,  gelatinous  sheath.  Cell  con- 
tents pale  blue-green  to  grey,  homogeneous  or  granulose.  (Tychoplank- 
tont) . 

Diam.  cells  (without  sheath)  5-7  ix,  (with  sheath)  6-12  /x;  length 
(without  sheath)  5-10  /x,  (with  sheath)  5-13  /x. 

Wolf  (rrr).^ 

Chroococcus  dispersus  (v.  Keissler)  Lemmermann.  PI.  1,  Fig.  2. 

Arkiv.  f.  Botanik  2,  No.  2:  102.  1904. 

Chroococcus  minor  var.  dispersus  v.  Keissler,  Verh.  d.  zool.-bot.  Ges.  Wien 
52:  311,  fig.  6.  1902. 

Cells  spherical,  4-16  or  more  united  to  form  spherical,  ovoid,  or  ir- 
regular colonies.  Individual  cells  some  distance  from  one  another, 
or  in  compact  groups  that  lie  some  distance  from  one  another  within 
the  colony.  Individual  cell  sheaths  frequently  confluent  with  the  col- 
onial sheath.  Cell  contents  homogeneous,  pale  to  bright  blue-green. 
(Euplanktont). 

Diam.  cells  (without  sheath)  3-4  /x;  (with  sheath)  6 /x.  Distance  be- 
tween cells  or  groups  of  cells  15-20  /x. 

Browns  (rr),  Pokegama  (1)  (rr). 

A species  that  is  closely  related  to  C.  limneticus  but  one  where  the 
number  of  cells  in  the  colony  is  usually  greater,  and  where  the  indi- 
vidual cells  or  groups  of  cells  are  some  distance  from  one  another. 

var.  minor  var.  nov.  PI.  1,  Fig.  3. 

Cells  smaller  than  the  typical  form  and  with  pale  grey  contents. 
(Euplanktont). 

Diam.  cells  1.  75-2.  5 /x. 

Long  (3)  (rrr),  Middle  McKenzie  (rr).  Palmer  (rr). 

♦ The  relative  abundance  of  the  individual  species  is  shown  by  the  following 
symbols;  (aaa)  very  abundant,  (aa)  abundant,  (a)  fairly  abundant,  (ccc)  very 
common,  (cc)  common,  (c)  fairly  common,  (s)  fairly  scarce,  (ss)  scarce, 
(sss)  very  scarce,  (r)  fairly  rare,  (rr)  rare,  (rrr)  very  rare. 


WISCONSIN  PHYTOPLANKTON 


29 


Chroococcus  Limneticus  Lemmermann.  PI.  1,  Fig.  4. 

Bot.  Cent.  76:  153.  1898;  Forschungsbr.  a.  d.  Biol.  Stat.  zu  Pl5n  7:  132,  pi.  1, 

figs.  22-23.  1899. 

Mature  cells  spherical  to  subspherical,  4-32  in  a free-floating  spheri- 
cal to  ovoid  colony.  Cells  fairly  close  together  and  equidistant  from 
one  another  within  the  colony,  sometimes  in  groups  of  2-4  but  with 
the  groups  lying  close  together.  Cell  division  in  all  three  planes  but 
a majority  of  the  cells  dividing  in  the  same  plane  and  giving  the  colony 
a somewhat  tabular  appearance.  Many  hemispherical  cells  present  be- 
cause of  the  slow  maturation  after  division.  Individual  cell  sheaths 
homogeneous  and  frequently  confluent  with  colonial  envelope.  Cell 
contents  homogeneous;  grey,  pale  to  bright  blue-green,  or  olive-green. 
(Euplanktont). 

Diam.  cells  (without  sheath)  6-12  fx,  (with  sheath)  8-14  /t. 

Balsam  (r),  Bear  (1)  (rr),  Bear  (2)  (rrr),  Bear  Trap  (sss),  Beasley  (rr), 
Beaver  (1)  (r),  Beaver  (2)  (ss),  Big  Butternut  (r),  Birch  (1)  (rr),  Birch  (2) 
(ss),  Birch  Island  (s),  Blake  (sss).  Bloom  (s),  Boulder  (rrr),  Browns  (s), 
Camp  (rr).  Catfish  (rr),  Chetac  (r),  Chetek  (rrr).  Cranberry  (sss),  Dunham 
(rr),  Dutchmans  (r).  Eagle  (rr).  East  (rr).  Fish  (rr).  Found  (rr),  Fowler 
(rr),  Grassy  (rr).  Grindstone  (rr).  Half  Moon  (rr),  Horseshoe  (1)  (r). 
Island  (rr),  Kawaguesaga  (rr),  Kimball  (rr),  Lac  Court  Oreilles  (rr).  Lac  la 
Belle  (r).  Little  Bass  (2)  (ss).  Little  Butternut  (rr).  Little  Rice  (2)  (rr). 
Little  Wood  (sss),  Loveless  (r),  Mary  (rr).  Middle  McKenzie  (r).  Mill  (rr), 
Mud  (1)  (rr).  Mud  (2)  (rr),  Mudhen  (r),  Nicaboyne  (r).  North  Twin  (rr), 
Oconomowoc  (rr).  Old  Taylors  (rr),  Pewaukee  (rr).  Pike  (rr).  Pine  Tree  (rr), 
Pokegama  (1)  (r),  Pokegama  (2)  (rrr),  Pokegama  (3)  (rr).  Poor  Farm  (rr). 
Poplar  (ss).  Reserve  (sss).  Rice  (1)  (r),  Round  (3)  (rr).  Sand  (1)  (s). 
Sand  (3)  (sss).  Sand  (4)  (rr).  Shell  (sss),  Silver  (2)  (r).  Spirit  (r).  Squir- 
rel (r).  Tenderfoot  (rrr),  Travis  (rrr).  Upper  Nashotah  (rr).  Upper  Nemah- 
bln  (rr).  White  Ash  (ss),  Whitefish  (s).  Wildcat  (rr),  Winnebago  (r).  Wolf 
(rr). 

This  is  preeminently  a plankton  species.  It  is  widely  distributed 
throughout  the  state  and  may  be  the  dominant  member  of  the  Myxo- 
phyceae  in  lakes  with  very  soft  water,  but  it  never  occurs  in  sufficient 
abundance  to  cause  the  familiar  phenomenon  of  blooming.  The  cells 
are  quite  variable  in  both  color  and  size. 


var.  SUBSAI..SUS  Lemmermann.  PI.  1,  Fig.  5. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  P16n  8:  84.  1901;  Arkiv  f.  Botanik  2:  No.  2: 

101,  pi.  1,  fg.  9.  1904. 

Cells  spherical  to  subspherical,  8-16-32  in  a somewhat  spherical  or 
broadly  ellipsoidal  colony  with  a wide  gelatinous  envelope.  Cell  con- 
tents homogeneous;  pale  to  bright  blue-green.  (Euplanktont). 


30 


WISCONSIN  PHYTOPLANKTON 


Diam.  cells  (without  sheath)  3. 5-4.5  /x;  (with  sheath)  4.5-5.5  fi. 

Big  Bass  (sss),  Blake  (rr),  Lac  Court  Oreilles  (ss),  Owen  (ss),  Paddock  (r). 

The  chief  distinction  of  this  and  the  following  varieties  is  in  the  size 
of  the  cells. 

var.  CARNEUS  (Chodat)  Lemmermann.  PI.  1,  Fig.  6. 

Arkiv  for  Botanik  2,  No.  2:  101.  1904. 

Cells  spherical  to  hemispherical,  4-8-16  irregularly  distributed 
throughout  a spherical  to  ovoid  gelatinous  matrix.  Individual  sheaths 
of  ceUs  confluent  with  the  colonial  envelope.  Cell  contents  homogene- 
ous; color  variable,  ochraceous,  grey,  blue-green  or  olive  green.  (Eu- 
planktont) . 

Diam.  cells  (without  sheath)  7-9  fi. 

Big  Bass  (ss),  Harris  (r),  Mendota  (rr),  Nancy  (r),  Oconomowoc  (rr). 

var.  DiSTANS  G.  M.  Smith.  PI.  1,  Pig.  7. 

Bull.  Torr.  Bot.  Cl.  43:  481,  pi.  26,  fig.  26.  1916. 

Cells  spherical  to  hemispherical,  8-32  in  a colony  and  lying  some 
distance  from  one  another  within  a spherical  to  ovoid,  hyaline,  homo- 
geneous, gelatinous,  colonial  envelope.  Individual  cell  sheaths  con- 
fluent with  the  colonial  envelope.  Cell  contents  homogeneous,  grey  to 
pale  blue-green  in  color.  (Euplanktont). 

Diam.  cells  (without  sheath)  6.5-7  /x. 

Bear  Trap  (s),  Birch  Island  (rr),  Browns  (sss),  Cochrane  (r).  Cranberry 
(sss),  Lindy  (rr),  Muskallonge  (rr). 

var.  ELEGANS  G.  M.  Smith.  PI.  1,  Pig.  8. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  619.  1918. 

Cells  circular  to  semicircular  in  front  view,  somewhat  flattened  in 
side  view.  Colonies  enclosed  by  a spherical,  homogeneous,  hyaline,  gel- 
atinous envelope.  Individual  sheaths  of  cells  conspicuous.  Cell  con- 
tents homogeneous;  generally  bright  blue-green  in  color.  (Euplank- 
tont). 

Diam.  cells  (without  sheath)  18-22  fx;  (with  sheath)  20-26  /x. 

Delavan  (rr). 

Chroococcus  giganteus  W.  West.  PI.  2,  Pig.  1. 

Jour.  Roy.  Micr.  Soc.  1892:  741,  pi.  10,  figs.  59-60.  1892. 

Cells  ordinarily  hemispherical,  rarely  becoming  spherical  or  ovoid 
after  division.  Solitary  or  in  colonies  of  two  (rarely  3-4)  enclosed  by 


WISCONSIN  PHYTOPLANKTON 


31 


a thick,  hyaline,  markedly  lamellate,  gelatinous  envelope.  Envelope  of 
individual  cells  conspicuous,  lamellated.  Cell  contents  distinctly  gran- 
ulose,  bright  blue-green.  (Tychoplanktont). 

Diam.  cells  (without  sheath)  54—58  ix\  (with  sheath)  67-70  /x. 

Mary  (rrr). 

Chroococcus  turgidus  (Kiitzing)  Nageli.  PI.  1,  Fig.  9. 

Gatt.  einz.  Algen  46.  1849;  G.  S.  West,  Brit.  Fresh w.  Algae  352,  fig.  166g.  1904. 

Cells  hemispherical,  spherical,  ovoid,  or  somewhat  flattened  by  mutual 
compression.  Cells  solitary  or  in  colonies  of  2-4  (rarely  8)  enclosed 
by  a thick,  hyaline,  generally  lamellated,  gelatinous  sheath.  Individual 
cells  also  with  hyaline,  lamellated  sheaths.  Cell  contents  homogeneous 
or  finely  granulose;  pale  to  bright  blue-green  or  rarely  brownish  in 
color.  ( Tychoplanktont ) . 

Diam.  cells  (without  sheath)  8-32  /x;  (with  sheath)  13-40  /x. 

Beasley  (rrr),  Beaver  (2X  (rr).  Browns  (rr),  Hillman  (rr),  Horse  (rrr), 
Oconomowoc  (rr),  Otter  (rr),  Rudolph  (rr).  Sand  (2)  (rr),  Upper  Turtle  (rr), 
Waubesa  (rrr). 


MERISMOPEDIA  Meyen  1839. 

Colonies  always  forming  flat,  curved,  or  irregularly  twisted  plates 
one  cell  in  thickness  with  the  constituent  cells  in  rectilinear  series  and 
usually  in  groups  of  four.'  Cells  spherical  to  subspherical  with  rounded 
ends,  hemispherical  for  some  time  after  division.  Individual  sheaths 
of  cells  rarely  distinct,  generally  confluent  with  the  copious,  hyaline, 
homogeneous,  colonial  envelope.  Number  of  cells  in  colony  4 — 4(K)0, 
cell  number  a multiple  of  two  in  young  colonies,  not  a multiple  of  two 
in  old  colonies.  Cell  contents  generally  homogeneous,  rarely  with 
pseudovacuoles.  Color  varying  from  grey  through  light  to  bright  blue- 
green,  rarely  rose  pink  to  violet. 

KEY  TO  THE  SPECIES. 


Cells  bright  blue-green M.  Elegans 

Cells  pale  blue-green. 

Cells  some  distance  from  one  another M.  Punctata 

Cells  close  together  (not  mutually  compressed). 

Diameter  of  cells  1.  5-2  /x M.  Tenuissima 

Diameter  of  cells  3-6  /x M.  Glauca 


32 


WISCONSIN  PHYTOPLANKTON 


Merismopedia  elegans  a.  Braun.  PL  2,  Fig.  6. 

in  Kiitzing,  Species  algarum  472.  1849;  G.  S.  West,  Brit.  Fresh w.  Algae  348: 
fig.  162^.  1904. 

Colonies  small  or  large,  of  16-4000  cells  regularly  arranged  in  recti- 
linear series  and  groups  of  four;  with  the  cell  number  a multiple  of 
two  in  young  colonies  but  becoming  irregular  in  arrangement  and  num- 
ber in  old  colonies.  Colonies  flat  except  when  containing  many  cells. 
Cells  spherical  to  broadly  ovoid,  with  homogeneous,  bright  blue-green 
contents.  (Facultative  Planktont). 

Cells  5-7  /A  broad,  5-9  fi  long. 

Carson  (rr),  Center  (rr),  Green  (1)  (rr),  Kegonsa  (rr),  Little  Bear  (rrr), 
Mendota  (r),  Monona  (r),  Mud  (1)  (rr),  Nancy  (r),  Upper  Nashotah  (rrr), 
Waubesa  (rr). 

This  alga  is  a good  example  of  a typical  benthitic  organism  that  is 
able  to  thrive  under  limnetic  conditions.  It  never  becomes  a conspicu- 
ous member  of  the  plankton  but  the  colonies  attain  a much  larger  size 
and  I have  observed  specimens  60-70  cells  broad  and  60-90  cells  long. 
There  is  a certain  amount  of  irregularity  in  such  colonies  so  exact  de- 
terminations of  cell  numbers  are  impossible. 

var.  major  var.  nov.  PL  2,  Fig.  6. 

Colonies  usually  containing  many  cells.  Cell  shape  the  same  as  in 
the  typical  form'.  Cell  contents  homogeneous,  bright  blue-green.  (Bu- 
planktont). 

Cells  10-11  fi  broad,  12-14  /jl  long. 

Beaverdam  (r),  Lindy  (rr). 

Merismopedia  glauca  (Ehrenberg)  Nageli.  PL  2,  Fig.  4. 

Gatt.  einz.  Algen  56,  pi.  1,  fig.  IP.  1849. 

Colonies  generally  containing  less  than  64  cells,  compactly  and  regu- 
larly arranged.  Cells  spherical  to  broadly  ellipsoid,  hemispherical  for 
some  time  after  division.  Cell  contents  homogeneous,  generally  pale 
blue-green.  (Facultative  Planktont). 

Diam.  cells  3-5  jm. 

George  (rr),  Jones  (rrr).  Lac  Court  Oreilles  (rrr).  Loon  (rrr),  Meta  (rr), 
Mill  (rr),  Waubesa  (rr). 

This  species  resembles  M.  punctata  in  the  size  of  the  cells  but  differs 
in  the  distance  between  the  cells. 


WISCONSIN  PHYTOPLANKTON 


33 


Merismopedia  punctata  Meyen.  PI.  2,  Fig.  3. 

Arch.  f.  Naturgesch.  5*:  67.  1839;  Kiitzing,  Tabulae  Phycol.  5:  18,  pi.  38,  /Ip.  3. 
1855. 

Colonies  small,  with  the  cells  some  distance  from  one  another  but 
regularly  arranged  in  rectilinear  series.  Cells  spherical  to  broadly 
ovoid  or  hemispherical.  Cell  contents  homogeneous,  grey  to  pale  blue- 
green.  (Tychoplanktont). 

Diam.  cells  2.5-3.5  /x. 

Big  Bass  (rrr). 

Merismopedia  tenuissima  Lemmermann.  PI.  2,  Fig.  2. 

Bot.  Cent.  76:  154.  1898;  Forschungsbr.  a.  d.  Biol.  Stat.  zu  P15n  7:  132,  pi.  1, 
Hg.  21.  1899. 

Colonies  rectangular,  free-floating,  generally  with  16-100  cells  lying 
close  together.  Rectilinear  arrangement  of  cells  soon  breaking  down 
and  not  evident  when  there  are  more  than  32  cells  in  a colony.  Col- 
onies distorted  when  of  any  size.  Cells  spherical  to  ovoid,  hemispheri- 
cal for  some  time  after  division.  Individual  sheath  of  cells  distinct 
or  confluent  with  colonial  envelope.  Cell  contents  homogeneous;  grey 
to  pale  blue-green.  (Facultative  Planktont). 

Diam.  cells  (without  sheath)  1.5-2  /x. 

Camp  (rr),  Little  Doctor  (rr),  Long  (3)  (r),  Mary  (rr). 

The  irregular  cellular  arrangement  is  very  common  in  older  colonies 
and  is  not  due  to  the  size  of  the  colony,  since  the  species  is  one  of  the 
smallest  of  the  genus,  but  to  irregularities  in  cell  division. 

COELOSPHAERIUM  Nageli  1849. 

Colonies  microscopic,  free-floating;  spherical,  ellipsoid,  reniform,  or 
irregular ; enclosed  by  a delicate,  hyaline,  homogeneous  or  radially  fibril- 
lar, gelatinous  envelope.  Cells  spherical,  ovoid,  ellipsoid,  sub-pyriform 
and  arranged  in  a single  layer  to  form  a hollow  sac  just  beneath  the 
periphery  of  the  colonial  envelope.  Cell  contents  homogeneous  and 
grey  to  bright  blue-green ; or  reddish  and  containing  numerous  pseudo- 
vacuoles.* 

Reproduction  by  vegetative  cell  division  in  three  directions. 


♦These  structures,  which  are  also  called  gas  vacuoles,  are  found  in  certain 
plankton  species  of  the  Myxophyceae.  They  are  minute  bodies,  which  are 
reddish  through  their  refractive  power,  that  occur  in  large  numbers  in  all 
cells  of  the  colony.  Various  functions  have  been  ascribed  to  them,  the  most 
probable  being  a means  of  protection  against  too  intense  light,  or  a giving  of 
greater  buoyancy  to  the  colony. 


3 


34 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 


Cells  spherical. 

Diameter  of  cells  not  exceeding  4 C.  Kuetzingiaum 

Diameter  of  cells  over  5 C.  Dtjbium 

Cells  ovoid  to  ellipsoid C.  Naegblianum 


CoELOSPHAERiUM  KuETZiNGiANUM  Nageli.  PI.  3,  Figs.  4-5. 

Gatt.  einz.  Algen  54,  pi.  1,  fig.  C.  1849. 

Colonies  spherical  to  subsplierical,  enclosed  by  a very  hyaline,  homo- 
geneous, gelatinous  envelope.  Cells  spherical  to  subspherical,  forming 
a single  layer,  with  the  individual  cells  or  pairs  of  cells  some  distance 
from  one  another  or  close  together.  Cell  contents  homogeneous,  with- 
out pseudovacuoles ; usually  grey  to  pale  blue-green,  rarely  bright  blue- 
green.  (Facultative  planktont). 

Diam.  cells  2.25-4  /x ; diam.  colonies  20-90  /x. 

Balsam  (rr),  Bass  (2)  (rr).  Bear  (3)  (r),  Bear  Trap  (rrr),  Beaverdam  (ss), 
Big  (ss).  Big  Butternut  (sss),  Birch  Island  (rrr),  Blake  (ss),  Bone  (rr). 
Browns  (rr),  Carson  (r).  Catfish  (r).  Clam  (ss),  Cochrane  (sss),  Crab  (rr). 
Cranberry  (ss).  Crawling  Stone  (sss),  Deer  (rr).  Diamond  (rrr),  Elizabeth 
(s).  Eagle  (ss).  Fence  (sss).  Fish  (rr),  Grindstone  (rr).  Green  (2)  (rr).  Half 
Moon  (r).  High  (sss),  Hillman  (ss).  Horseshoe  (1)  (rrr),  Kegonsa  (s).  Kit- 
ten (rr).  Island  (ss).  Lac  la  Belle  (rr),  Lindy  (rr).  Little  Bear  (rrr).  Little 
Butternut  (r).  Little  Crooked  (rr).  Little  Rice  (1)  (ss).  Little  Wood  (s), 
Long  (2)  (rr).  Long  (3)  (rr).  Loveless  (sss),  Mary  (s),  Mendota  (s),  Mer- 
cer (rrr).  Mill  (rrr).  Mud  (1)  (cc).  Mud  (2)  (r),  Mudhen  (s),  Nancy  (rrr), 
Nicaboyne  (rr),  North  Turtle  (ss),  Oconomowoc  (r),  Owen  (rrr).  Paddock 
(ss).  Palmer  (ss),  Pardee  (cc),  Pewaukee  (rr).  Pine  (2)  (rr).  Fine  Tree  (rr), 
Pokegama  (1)  (sss),  Pokegama  (2)  (r),  Pokegama  (3)  (rrr).  Poplar  (ss), 
Reserve  (ss).  Rice  (1)  (rr).  Rock  (sss).  Round  (3)  (sss).  Sand  (1)  (rr), 
Sand  (3)  (rr).  Sand  (4)  (r).  Silver  (1)  (ccc).  Silver  (2)  (ss),  South  Turtle 
(ss),  Spirit  (ss),  iSunday  (r).  Tamarack  (rr).  Tenderfoot  (sss).  Tied  Canoe 
(rrr).  Upper  Nemahbin  (rrr).  Upper  Turtle  (sss).  White  Ash  (sss).  White- 
fish  (s),  W’hite  Sand  (sss).  Wildcat  (rr).  Wild  Goose  (rr),  Winnebago  (rr). 
Wolf  (r). 

The  gelatinous  sheath  is  generally  so  delicate  that  it  is  necessary  to 
use  Errera’s  method  of  mounting  colonies  in  dilute  India  ink  to  demon- 
strate its  presence.  The  specific  limits  of  this  species  as  established 
by  different  authors  frequently  includes  C.  Naegelianum  as  a synonym. 
C.  Kuetzingianum  and  C.  Naegelianum  are  two  well  defined  species  that 
differ  in  colony  shape^  cell  shape,  occurrence  of  pseudovacuoles,  struc- 
ture of  colonial  envelope,  and  relative  abundance.  C.  Kuetzingianum 
is  a species  that  is  widely  distributed  throughout  the  state  but  one  which 
rarely  becomes  a dominant  member  of  the  plankton  and  never  occurs 
in  sufficient  abundance  to  cause  blooming. 


V/I8C0NSIN  PHYTOPLANKTON 


35 


CoELOSPHAERiuM  DUBiUM  Grunow.  PI.  3,  Fig.  7. 

in  Rabenhorst,  Flora  Eur.  Algarum  2:  55.  1865;  Scbmula,  Beibl.  z.  Hedwigla 
S7:  (47),  figs.  1-2.  1898. 

Colonies  spherical  to  irregular,  with  three  or  four  smaller  colonies 
frequently  enclosed  by  a common  gelatinous  envelope.  Colonial  en- 
velope firm,  hyaline,  and  homogeneous.  Cells  in  a single  layer  and 
very  close  together  at  the  periphery  of  the  colonial  envelope.  Cell  con- 
tents homogeneous  or  with  p seudo vacuoles ; blue-green  in  color.  (Fac- 
ultative Planktont). 

Cells  5-7  fx  in  diameter.  Single  colonies  up  to  150  /x  in  diam ; com- 
pound colonies  up  to  300  fx. 

Mud  (3)  (rr). 


CoELOSPHAERiUM  Naegelianum  Unger.  PI.  3,  Fig.  6;  PI.  4,  Fig.  1. 

Denkschr.  d.  kais.  Ak.  d.  Wiss.  Wien  7:  196.  1854;  Leitgeb,  Mitt.  d.  naturw. 

Ver.  Steiermark  2,  Heft  1:  72,  pi.  2,  figs.  1-6.  1869;  Borge,  Bot.  Not.  1900: 

10,  pi.  1,  figs.  5a-5b.  1900. 

Gomphosphaeria  Naegeliana  (Unger)  Lemmermann.  Kryptogamenfl.  d. 
Mark  Brandenburg  3,  Algen  1:  80,  44,  fig.  19.  1907;  Bachmann,  Arch.  f.  Hy- 

drobiol.  u.  Planktonkde.  3:  60,  figs.  IIP-IIP.  1908. 

Colonies  spherical,  ovoid,  renif orm  or  irregular ; with  a wide,  hyaline, 
gelatinous  envelope  that  is  at  times  radially  fibrillar  in  structure.  Cells 
ovoid  to  ellipsoid,  radially  arranged  in  a single  layer  some  distance  be- 
neath the  periphery  of  the  colonial  envelope,  usually  close  together  but 
not  mutually  compressed.  Cell  contents  rarely  homogeneous  and  pale 
to  bright  blue-green  or  grass-green ; usually  with  numerous  pseudovacu- 
oles and  reddish  to  brownish  in  color.  (Euplanktont). 

Cells  2-3  IX  broad ; 3.5-6  /a  long. 

Adelaide  (ss),  Amicoy  (ss).  Balsam  (ss).  Bear  (1)  (s).  Bear  (2)  (rr), 
Bear  (3)  (s),  Bear  Trap  (sss),  Beaverdam  (cc).  Big  (ccc).  Big  Butternut 
(r).  Big  McKenzie  (ss).  Big  St.  Germaine  (rr),  Birch  (1)  (ccc),  Birch  (2) 
(aa),  Birch  Island  (rrr),  Blake  (rr).  Bloom  (ss),  Bone  (ss),  Boulder  (rr). 
Browns  (rr),  Camp  (c).  Catfish  (aa),  Center  (aa),  Chetac  (aa).  Clam  (c), 
Clare  (rr).  Crab  (sss).  Cranberry  (aa).  Devils  (1)  (rr).  Devils  (2)  (ss). 
Deer  (rr).  Duck  (c).  Dummy  (rrr),  Elizabeth  (cc),  Fish  (sss).  Found  (ss), 
Fowler  (ss),  Granite  (ss).  Grindstone  (rr).  Half  Moon  (s),  Hillman  (s). 
Hooker  (rr).  Horseshoe  (1)  (ss).  Horseshoe  (2)  (rrr).  Island  (cc),  Jennie 
(rr),  Kawaguesaga  (sss).  Kitten  (rrr),  Kegonsa  (aa).  Lac  du  Flambeau  (rr), 
Lac  la  Belle  (r),  Laura  (aa),  Lindy  (rr).  Little  Bass  (2)  (rr).  Little  Butter- 
nut (rr).  Little  Rice  (1)  (cc).  Long  (1)  (rr).  Long  (2)  (a).  Loon  (rr).  Lost 
(aa),  Lower  Nemahbin  (r).  Marl  (rr),  Mendota  (cc),  Mercer  (ss),  Middle 
McKenzie  (cc),  Mill  (rr),  Minocqua  (rr),  Monona  (aa).  Mud  (1)  (cc).  Mud 
(3)  (aa),  Mudhen  (rr),  Nancy  (c),  Nicaboyne  (r).  No  Mans  (aa).  North 
Twin  (cc).  North  Turtle  (aa).  Number  One  (ss),  Oconomowoc  (rr),  Okauchee 


WISCONSIN  PHYTOPLANKTON 


rfb 

(r),  Otter  (rr).  Paddock  (c),  Palmer  (ss),  Pardee  (rr),  Pewaukee  (ss), 
Plum  (ss),  Pokegama  (1)  (c),  Pokegama  (2)  (sss),  Pokegama  (3)  (a),  Pop- 
lar (r),  Prairie  (s),  Reserve  (ss),  Rainbow  (r),  Rice  (1)  (cc),  Rock  (a), 
Rooney  (aa).  Round  (1)  (rrr).  Round  (2)  (ss),  Round  (3)  (ss),  St.  Croix 
(cc),  Sanford  (r),  Sand  (1)  (ss).  Sand  (2)  (rr),  Sand  (3)  (rr),  Sand  (4) 
(rr).  Silver  (2)  (c),  tSishebogema  (aa).  South  Turtle  (sss).  Upper  Nashotah 
(rr).  Upper  Nemahbin  (rr).  Upper  Turtle  (s),  Wapagossett  (cc),  Waubesa 
(cc).  White  Ash  (rr),  Whitefish  (cc).  White  Sand  (rrr).  Wildcat  (rrr),  Win- 
nebago (cc),WoK  (rrr). 

The  radial  fibrillar  structure  at  the  periphery  of  the  gelatinous  en- 
velope is  also  found  at  times  in  the  center  of  the  colony.  These  radia- 
tions have  been  compared  by  some  to  the  gelatinous  strands  found  in 
GomphospJiaeria  and  the  species  transferred  to  that  genus.  I have 
preferred  to  keep  the  alga  in  the  genus  where  it  was  first  described. 
This  alga  is  one  of  the  important  members  of  the  Myxophyceae  in  the 
formation  of  blooms  but  it  is  rarely  found  as  the  sole  constituent  of 
any  bloom.  Bachmann’s  figures  of  the  alga  are  quite  characteristic. 

GOMPHOSPHAERIA  Kiitzing  1836. 

Colonies  microscopic,  spherical  to  ellipsoid,  embedded  in  a copious, 
hyaline,  solid,  homogeneous,  gelatinous  envelope.  Cells  spherical 
to  pyriform,  solitary  or  in  pairs,  generally  lying  some  distance  from 
one  another  and  forming  a layer  one  cell  in  thickness  towards  the  pe- 
riphery of  the  colonial  envelope.  Central  portion  of  colonial  envelope 
containing  a denser  core  from  which  projections  radiate  to  the  base  of 
the  cells.  Individual  sheaths  of  cells  distinct  or  confluent  with  the 
colonial  envelope.  Cell  contents  homogeneous,  rarely  granulose;  grey 
to  light  or  bright  blue-green. 

Reproduction  by  alternate  vegetative  division  of  cells  in  three  planes. 

KEY  TO  THE  SPECIES. 


Cells  spherical  G.  Lacustris 

Cells  pyriform  to  cardioid G.  Afonina 


Gomphosphaeria  lacustris  Chodat.  PI.  4,  Fig.  5. 

Bull.  Herb.  Boiss.  6:  180,  figs.  1898;  W.  & G.  S.  West,  Trans.  Roy.  Irish 

Acad.  33,  Sec.  B:  112,  pi.  11,  figs.  24-27.  1906. 

Colonies  small,  generally  spherical  or  subspherical,  rarely  reniform; 
with  a hyaline,  homogeneous,  gelatinous  envelope.  Cells  spherical  to 
broadly  ellipsoid,  irregularly  spaced  to  form  a single  layer  one  cell  in 
thickness  beneath  the  periphery  of  the  colonial  envelope.  Individual 
cell  sheaths  confluent  with  colonial  envelope.  Central  portion  of  col- 
ony containing  a core  of  denser  radiating  gelatinous  strands  that  run 


WISCONSIN  PHYTOPLANKTON 


37 


to  the  base  of  the  cells.  Cell  contents  homogeneous;  grey  to  pale  or 
bright  blue-green,  rose  colored  in  rare  instances.  (Euplanktont). 
Cells  1. 5-2.5  IX  broad,  1.5-4  /x  long.  Colonies  rarely  over  40  fx  in  diam. 

Bear  (1)  (rr),  Beaverdam  (c),  Big  McKenzie  (ss),  Blake  (sss)^  Cochrane 
(r),  Deer  (rr),  Diamond  (r),  Dunham  (c),  Fish  (c),  Half  Moon  (rr).  Island 
(rr),  Kawaguesaga  (r).  Lac  Court  Oreilles  (ss),  Llndy  (sss).  Little  Bass  (2) 
(rr),  Long  (1)  (rr).  Loon  (rr),  Mendota  (s),  Mercer  (ss).  Middle  McKenzie 
(ss),  Mudhen  (ss),  Nicaboyne  (r).  North  Twin  (r),  Pardee  (rr).  Plum  (rr), 
Pokegama  (3)  (rr).  Sand  (1)  (r).  Sand  (2)  (rr).  Sand  (4)  (rr),  Spirit  (r), 
Squirrel  (sss).  Star  (sss),  Wolf  (r). 

The  colonies  of  this  species  resemble  those  of  Coelosphaerium  Kuetz- 
ingianum  in  cell  shape  and  arrangement  but  differ  in  the  radiating 
strands  of  gelatinous  material  running  from  the  center  of  the  colony 
to  the  base  of  the  cells.  The  gelatinous  envelope  is  very  delicate  and 
cells  frequently  break  away  leaving  the  central  mass  of  gelatinous  radi- 
ations floating  by  itself. 

Gomphosphaeria  aponina  Kiitzing.  PI.  4,  Figs.  2-3. 

Decades  16:  No.  151.  1836;  G.  S.  West,  Brit.  Freshw.  Algae  349,  fig.  163g. 
1904. 

Colonies  small,  spherical  to  subspherical,  with  a fairly  thick,  hya- 
line, homogeneous,  gelatinous  envelope.  Cells  pyriform  to  cuneate, 
cardioid  just  before  division;  sparsely  scattered  and  in  a single  layer 
some  distance  beneath  the  periphery  of  the  colonial  envelope.  Indi- 
vidual sheaths  of  cells  generally  distinct,  attached  at  the  base  to  the 
dense  gelatinous  strands  radiating  from  the  center  of  the  colony.  Cell 
contents  homogeneous  or  finely  granulose;  without  pseudovacuoles; 
generally  a bright  blue-green.  (Tychoplanktont). 

Cells  4-5  fx  wide  at  the  greatest  breadth,  8-15  /x  long.  Diam.  colonies 
50-90  fx. 

Beaverdam  (sss).  Big  McKenzie  (rrr).  Browns  (rr).  Center  (rr),  Eagle 
(rr),  Elizabeth  (rr),  Hillman  (rr),  Kegonsa  (rrr).  Lower  Nemahbin  (rr), 
Mendota  (rr),  Mary  (rr),  Monona  (rrr),  Mudhen  (rr).  North  Turtle  (rrr). 
Otter  (rrr),  Pewaukee  (rr).  Pine  (1)  (rrr).  Plum  (rrr).  Silver  (2)  (rr),  Sil- 
ver (3)  (rr).  South  Turtle  (rr),  Waubesa  (r). 

var.  coRDiFORMis  Wolle.  PI.  4,  Fig.  4. 

Bull.  Torr.  Bot.  Cl.  9:  25,  pi.  13,  fig.  11.  1882. 

Cells  considerably  larger  than  in  the  typical  form  and  markedly 
heart  shaped  instead  of  pyriform.  Individual  sheaths  of  cells  conspicu- 
ous. Cell  contents  bright  blue-green.  (Tychoplanktont). 

Greatest  breadth  of  cells  6-13  fx ; length  9-20  /x. 

Bloom  (rrr). 


38 


WISCONSIN  PHYTOPLANKTON 


The  cells  of  the  Wisconsin  individuals  are  somewhat  longer  than 
Wolle  found  them,  his  measurements  for  the  length  of  the  cell  varying 
from  9-16  fi. 


MICROCYSTIS  Kiitzing  1833. 

Colonies  free-floating;  spherical,  elongate,  irregular,  or  perforate  to 
form  reticulate  or  clathrate  masses  of  microscopic  or  macroscopic  size. 
Frequently  occurring  in  sufficient  quantities  to  give  the  water  a verdi- 
gris-green color.  Envelope  of  colonies  generally  copious,  delicate  to 
firm.  Cells  small,  spherical,  distributed  in  a solid  mass  throughout  the 
colony  and  densely  aggregated.  Individual  cell  sheath  confluent  with 
colonial  envelope.  Cell  contents  homogeneous  or  with  numerous  pseudo- 
vacuoles ; light  to  dark  blue-green,  olive-green,  or  rose  colored. 

Reproduction  by  vegetative  division  of  cells  in  three  directions. 

Certain  species  of  the  genus  occur  in  prodigious  quantities  and  cause 
the  familiar  blooming  of  lakes.  These  species  contain  pseudovacuoles, 
while  species  without  pseudovacuoles  rarely  occur  in  quantity. 

KEY  TO  THE  SPECIES. 

Cells  with  numerous  pseudovacuoles. 

Several  colonies  enclosed  by  the  same  envelope M.  Ichthyoblabe 

Colonies  not  differentiated  into  several  within  the  same  envelope. 

Colony  entire,  not  perforate M.  Flos-Aquae 

Colony  saccate  and  perforate M.  Aeruginosa 

Cells  without  pseudovacuoles. 

Diameter  of  cells  less  than  1.5  /x M.  Inceeta 

Diameter  of  cells  2-3  jx M.  Pulvera 

Microcystis  ichthyoblabe  Kiitzing. 

Phycol.  generalis  170.  1843. 

Polycystis  ichthyoblabe  Kiitzing,  Tabulae  Phycol.  1:  7,  pi.  8.  1845. 

Colonies  spherical  or  irregular,  fragmented  into  several  distinct  sub- 
colonies, each  with  its  own  gelatinous  envelope,  and  with  the  sub-col- 
onies enclosed  by  a common  gelatinous  envelope.  Cells  spherical,  close 
together.  Individual  cell  sheaths  confluent  with  colonial  envelope.  Cell 
contents  pale  to  bright  blue-green.  Generally  containing  numerous 
pseudovacuolcs.  (Facultative  Planktont). 

Diam.  cells  2^  /x. 

Catfish  (rr),  Clear  (rr),  Kawaguesaga  (ss),  Minocqua  (r). 


WISCONSIN  PHYTOPLANKTON 


39 


Microcystis  FLOS-AQUAE  (Wittrock)  Kirckner.  PL  5,  Fig.  1. 
in  Engler  & Prantl,  D.  nat.  Pflanzenfam.  1 (Abt.  1&) : 56,  fig.  49j^.  1900. 

Colonies  spherical  to  ovoid,  rarely  elongate ; frequently  reaching  a 
macroscopic  size.  Cells  compactly  and  evenly  distributed  within  a very 
delicate,  hyaline,  homogeneous,  gelatinous  envelope.  Margins  of  colony 
not  sharply  defined.  Cell  contents  rarely  homogeneous  and  grey  to 
pale  blue-green;  usually  with  pseudovacuoles  and  reddish  in  color. 
Plant  mass  yellowish  to  verdigris-green.  (Euplanktont). 

Diam.  cells  3. 5-6.5  ju,. 

Bear  (2)  (rr),  Big  St.  Germain  (rr),  Birch  (1)  (c),  Birch  Island  (sss), 
Browns  (cc),  Catfish  (ss),  Center  (ss),  Cochrane  (sss),  Duck  (ss),  Dunham 
(rr),  Pishtrap  (rr).  Found  (sss),  Fowler  (rr),  High  (rr).  Horseshoe  (1)  (rr), 
Kegonsa  (cc).  Loveless  (r).  Lower  Nashotah  (rr).  Lower  Nemahbin  (r), 
Mendota  (aa),  Mercer  (rrr),  Monona  (aa).  Mud  (3)  (cc),  Nagawicka  (rr). 
No  Mans  (r).  North  Turtle  (ss),  Oconomowoc  (ss).  Paddock  (ss).  Palmer  (ss), 
Pardee  (ss).  Plum  (ss),  Pokegama  (1)  (ss),  Rainbow  (r).  Rock  (s).  Rose 
(ss).  Sand  (3)  (r).  Shell  (rr),  Sishebogema  (ss).  South  Turtle  (ss).  Squirrel 
(rr),  Star  (ss).  Tamarack  (ss).  Tenderfoot  (rr).  Upper  Nashotah  (rrr),  Wapa- 
gossett  (ss),  Waubesa  (ss),  Whitefish  (ss),  Winnebago  (cc). 

Microcystis  aeruginosa  Kiitzing.  PI.  5,  Figs.  2-3. 

Tabulae  Phycol.  1:  6,  pi.  8.  1845. 

Clathrocystis  aeruginosa  (Kiitzing)  Henfrey,  Trans.  Micr.  Soc.  London  N.  S. 
4:  53,  pi,  4,  figs.  28-36.  1856  (in  Quart.  Jour.  Micr.  Sci.  4:  1856):  Bachmann, 
Arch.  f.  Hydrobiol.  u.  Planktonkde.  3:  61,  figs.  IW-IV®.  1908. 

Colonies  spherical  to  subspherical  when  young,  later  becoming  saccate 
and  ultimately  reticulate  and  clathrate.  Gelatinous  envelope  of  colony 
homogeneous,  hyaline,  and  indistinct.  Colonies  frequently  occurring 
in  sufficient  quantity  to  color  water  a bright  green.  Cells  spherical  to 
subspherical,  evenly  distributed  throughout  the  colony  and  close  to- 
gether. Cell  contents  rarely  homogeneous  and  grey  to  pale  or  bright 
blue-green;  usually  with  numerous  pseudovacuoles  and  reddish.  (Eu- 
planktont). 

Diam.  cells  3-4  p. 

Balsam  (ss).  Bear  (3)  (rr).  Big  Butternut  (ss).  Bloom  (ccc).  Bone  (ss). 
Browns  (cc).  Center  (rr).  Clam  (r).  Crooked  (rrr),  Delavan  (sss),  Desmoines 
(ss).  Devils  (2)  (rr).  Duck  (rr),  Dutchmans  (rrr).  Eagle  (ccc),  Elizabeth 
(cc).  Pish  (ss),  Fowler  (rr).  Grassy  (ss).  Grindstone  (rr).  Half  Moon  (ss). 
Hooker  (ss).  Horseshoe  (1)  (rr),  Kawaguesaga  (rr),  Kegonsa  (a),  Kimball 
(ss).  Lac  du  Flambeau  (rr),  Lac  la  Belle  (rr).  Lake  of  the  Woods  (r).  Little 
Bass  (2)  (sss).  Little  Butternut  (cc),  Little  Crooked  (ss).  Little  Wood  (ss), 
Loveless  (ss),  Mendota  (a),  Meronk  (ss).  Mill  (sss),  Monona  (cc).  Mud  (2) 
(r),  Mudhen  (ss),  Nancy  (ss),  Nicaboyne  (ss).  North  Turtle  (ss),  North 
Twin  (cc),  Oconomowoc  (rrr).  Old  Taylors  (r),  Otter  (rr),  Owen  (rrr),  Par- 
dee (ss),  Pewaukee  (ss),  Pokegama  (2)  (rr),  Pokegama  (3)  (ss),  Prairie 


40 


WISCONSIN  PHYTOPLANKTON 


(S8S),  Rice  (1)  (rr),  Rooney  (r).  Sand  (1)  (ss),  Sand  (4)  (rr),  Shell  (rr), 
Silver  (2)  (ss),  Travis  (rr),  Upper  Turtle  (ss),  Waubesa  (cc).  White  Ash 
(sf).  Wildcat  (ss).  Wolf  (rr). 

var.  MAJOR  (Wittrock)  G.  M.  Smith.  PL  4,  Fig.  6. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18*:  535.  1916. 

Mature  colonies  elongate;  irregular,  saccate,  or  clathrate.  Colonial 
envelope  much  firmer  than  in  typical  form  and  with  larger  cells.  (Eu- 
planktont) . 

Diam.  cells  5.5-G.5  fi. 

Center  (rr),  Mendota  (ss),  Nancy  (sss),  St.  Croix  (rr).  Vermilion  (cc). 

Microcystis  incerta  Lemmermann.  PI.  5,  Fig.  4. 

Abh.  Naturw.  Ver.  Bremen  17:  342.  1903;  Kryptogamenfl.  d.  Mark  Branden- 

burg 3;  Algen  1:  76,  44,  fig.  12.  1907. 

Colonies  spherical  or  somewhat  elongate,  enclosed  by  a hyaline,  homo- 
geneous, and  very  delicate  gelatinous  envelope.  Cells  small,  very  close 
together  but  equidistant  from  one  another.  Cell  contents  homogeneous, 
without  pseudovacuoles;  grey  to  pale  blue-green  in  color.  (Faculta- 
tive Planktont) . 

Diam.  cells  1-2  fi. 

Camp  (rr),  Chetek  (r).  Hooker  (s).  Prairie  (r),  Whitefish  (rr),  Winne- 
bago (c). 

The  cells  of  this  species  are  very  similar  in  appearance  to  those  found 
in  Aphanocapsa  elachista  and  A.  delicatissima  but  their  compact  ar- 
rangement shows  that  the  alga  is  a 3Iicrocystis  and  not  an  Aphanocapsa. 

Microcystis  pulvera  (Wood)  Migula. 

in  Thomd,  Flora  v.  Deutschl.,  Deutsch.-Osterr.  u.  d.  Schw.  6,  Kryptogamen  2, 
Algen  1:36.  1907. 

Anacystis  pulverus  Wood.  Wolle,  Preshw.  Algae  of  U.  S.  329,  pi.  210,  fig.  25. 
1887. 

Colonies  spherical  or  elongate,  with  a very  delicate,  hyaline,  gela- 
tinous envelope.  Cells  spherical,  very  closely  crowded  together  and 
forming  a solid  mass.  Cell  contents  homogeneous,  without  pseudovacu- 
oles ; grey,  pale  olive-green,  or  blue-green  in  color.  (Facultative  Plank- 
tont) . 

Diam.  cells  2-3  p. 

Browns  (rr),  Mill  (rrr),  Pardee  (ss),  Sunday  (r),  Winnebago  (sss). 

Since  the  specific  difference  between  this  and  the  foregoing  species 
is  mainly  one  of  cell  size  it  might  be  better  to  consider  M.  incerta  a 
variety  of  M.  pvlvera. 


WISCONSIN  PHYTOPLANKTON 


41 


APHANOCAPSA  Nageli  1849. 

Cells  united  to  form  spherical,  ovoid,  or  amorphous  colonies  of  micro- 
scopic or  macroscopic  size.  Colonies,  hyaline,  yellow,  brown,  or  blue- 
green  in  color.  Cells  spherical,  equally  distributed  throughout  the 
colony  but  always  some  distance  from  one  another;  generally  solitary, 
rarely  in  clusters.  Individual  sheaths  of  cells  confluent  with  the  homo- 
geneous, hyaline  or  colored,  colonial  envelope.  Cell  contents  homogene- 
ous ; usually  pale  to  bright  blue-green  or  grey  in  color. 

Reproduction  by  vegetative  division  of  cells  in  three  directions. 


KEY  TO  THE  SPECIES. 


Cells  growing  within  gelatinous  envelope  of  other  algae A.  Endophytica 

Cells  forming  free-floating  or  sessile  colonies. 

Cell  contents  grey  to  pale  blue-green. 

Diameter  of  cells  3. 5-4. 5 fi A.  Pulchra 

Diameter  of  cells  less  than  3 At. 

Cell  diameter  not  exceeding  1 fx A.  Delicatissima 

Cell  diameter  1.5-2.5  fx A.  Elachista 

Cell  contents  brightly  colored,  generally  blue-green. 

Diameter  of  cells  3.5-5  fx A.  Grevillei 

Diameter  of  cells  5-6  a* A.  Rivularis 


Aphanocapsa  delicatissima  W.  & Gr.  S.  West.  PI.  2,  Fig.  7. 

Jour.  Linn.  Soc.  Bot.  40  : 431,  yl.  19,  -figs.  2-3.  1912. 

Colonies  small,  spherical,  ovoid  or  irregular,  free-floating.  Colonial 
envelope  gelatinous,  homogeneous,  hyaline  or  ochraceous.  Cells  spheri- 
cal, very  small,  more  or  less  remote  from  one  another.  Cell  contents 
homogeneous,  grey  to  pale  blue-green.  (Euplanktont). 

Cells  .5-.75  fx  in  diam. ; colonies  15-30  fx  broad,  15-50  lonar. 

Big  Butternut  (r).  Chain  (r),  Little  Butternut  (ss).  Loveless  (ss),  Mendota 
(s),  Poor  Farm  (r). 

The  cells  of  this  species  are  smaller  than  many  bacteria  and  during 
the  first  two  year  ^s  study  of  the  plankton  flora  these  small  colonies  were 
considered  bacteria  and  not  recorded  so  that  the  record  for  distribution 
is  far  from  complete.  When  the  colonies  are  of  any  considerable  size 
the  mass  of  cells  has  a decided  blue-green  color  so  that  the  organism 
must  be  called  a blue-green  bacterium  or  a blue-green  alga  of  bacterial 
size.  The  latter  view  seems  to  be  the  more  logical.  It  is  very  probable 
that  the  bacteria  have  been  derived  from  the  blue-green  algae  and  the 
Wests’  discovery  of  blue-green  algae  of  bacterial  size  is  very  suggestive. 


42 


WISCONSIN  PHYTOPLANKTON 


Aphanocapsa  elachista  var.  conferta  W.  & G.  S.  West.  PL  2,  Fig.  8. 
Jour.  Linn.  Soc.  Bot.  40:  432,  pi.  19,  fig.  1.  1912, 

Colonies  small,  spherical,  ovoid,  or  irregular ; with  the  cells  enclosed 
by  a gelatinous,  homogeneous,  hyaline  or  ochraceous  envelope.  Indi- 
vidual sheaths  of  cells  confluent  with  colonial  envelope.  Cells  spheri- 
cal, fairly  close  together.  Cell  contents  homogeneous,  grey  to  pale 
blue-green.  (Euplanktont) . 

Diam.  cells  1. 6-2.0  [x.  Colonies  up  to  75  /a  broad  and  100  fi  long. 

Birch  Island  (rr),  Crawling  Stone  (rrr),  Deer  (ss),  Lindy  (r),  Nancy  (r), 
Pine  Tree  (ss),  Silver  (2)  (rr). 

var.  planctonica  var.  nov.  PI.  3,  Pig.  3. 

Cells  spherical,  some  distance  from  one  another.  Sheath  enclosing 
colony  always  hyaline.  Contents  of  cells  pale  grey.  (Euplanktont). 

Diam.  cells  2-3  fx. 

Bear  (1)  (s).  Bear  Trap  (rr),  Poplar  (ss).  Round  (3)  (rr).  Sand  (1)  (r). 

Differing  from  the  typical  form  in  the  larger  cell  size  and  grey  color 
of  the  cell  contents. 

Aphanocapsa  endophytica  sp.  nov.  PI.  2,  Pig.  10. 

Colonies  endophytic  within  the  gelatinous  sheath  of  Microcystis  col- 
onies and  with  their  envelopes  confluent  with  the  envelope  of  the  host 
colony.  Cells  spherical,  equidistant  from  one  another  or  in  small 
clumps.  Cell  contents  homogeneous,  grey  to  bright  blue-green.  (Eu- 
planktont). 

Diam.  cells  2 jx. 

Poor  Farm  (ss). 

The  occurrence  of  bacteria  in  the  gelatinous  envelope  of  colonial 
Myxophyceae  is  a familiar  phenomenon  to  the  limnologist.  The  blue- 
green  color  of  the  cells  endophytic  within  the  envelopes  of  Microcystis 
colonies  in  Poor  Farm  Lake  precludes  their  recognition  as  bacteria. 
(See  G.  S.  West’s  remarks  concerning  a similar  endophytic  Aphano- 
thece  in  Jour.  Linn.  Soc.  Bot.  40:  432.  1912). 

Aphanocapsa  pulchra  (Kiitzing)  Rabenhorst.  PI.  2,  Pig.  9. 

Flora  Eur.  Algarum  2:  49.  1865. 

Colonics  macroscopic  or  microscopic,  free-floating  or  sessile,  generally 
spherical  to  ovoid  when  found  in  the  plankton.  Sheath  of  colony  gela- 
tinous, firm,  hyaline,  homogeneous;  with  the  cells  some  distance  from 


WISCONSIN  PHYTOPLANKTON 


43 


one  another.  Individual  cell  sheaths  confluent  with  the  colonial  en- 
velope. Cell  contents  homogeneous,  grey  to  pale  blue-green.  (Tycho- 
planktont) . 

Diam.  cells  3. 5-4.5  jx. 

Beaver  (r),  Beaverdam  (sss),  Harris  (rrr),  Lac  Court  Oreilles  (ss),  Win- 
nebago (rr). 

Aphanocapsa  grevillei  (Hassall)  Kabenhorst.  PI.  3,  Fig.  1. 

Flora  Eur.  Algarum  2:  50.  1865;  G.  S.  West,  Brit.  Freshw.  Algae,  351,  -fig- 

165^.  1904. 

Colonies  free-floating  or  sessile ; spherical  to  ellipsoid  when  free-float- 
ing, dirty  green  in  color.  Cells  spherical,  solitary  or  in  pairs  and  some- 
what crowded.  Cell  contents  homogeneous  or  finely  granulose,  bright 
blue-green  in  color.  (Facultative  Planktont). 

Diam.  cells  3.5-5  ix, 

Beaverdam  (rr),  Birch  (ss),  Camp  (ss),  Chetac  (sss),  Muskallonge  (rr). 
Rice  (1)  (rr).  Silver  (1)  (rrr),  Whitefish  (ss). 

Aphanocapsa  rivularis  ( Carm. ) Rabenhorst.  PI.  3,  Fig.  2. 

Flora  Eur.  Algarum  2:  49.  1865;  Cooke,  Brit.  Freshw.  Algae  210,  pi.  86,  fig.  2. 
1884. 

Colonies  free-floating  or  sessile;  spherical,  tubular,  or  irregular  in 
shape.  Cells  spherical,  solitary  or  in  pairs  and  some  distance  from  one 
another  within  the  colony.  Individual  sheaths  of  cells  confluent  with 
the  hyaline,  homogeneous,  colonial  envelope.  Cell  contents  homogene- 
ous or  finely  granulose;  bright  blue-green  in  color.  (Tychoplanktont). 

Diam.  cells  5-6  ju. 

star  (rrr). 

APHANOTHECE  Nageli  1849. 

Colonies  free-floating,  sessile,  or  endophytic;  spherical  or  expanded 
into  amorphous  masses  and  enclosed  by  a firm,  copious,  homogeneous, 
hyaline  or  colored  envelope.  Cells  oblong  to  cylindrical,  with  rounded 
ends.  Cells  forming  a solid  mass  distributed  throughout  the  colonial 
envelope  but  lying  some  distance  from  one  another.  Individual  cell 
sheaths  indistinct,  confluent  with  the  colonial  envelope.  Cell  contents 
homogeneous  or  finely  granulose,  never  with  pseudovacuoles ; grey,  light 
to  bright  blue-green,  or  olive-green  in  color. 

Reproduction  by  vegetative  division  of  cells  in  three  planes,  but  with 
cell  divisions  always  taking  place  at  right  angles  to  the  long  axes  of 
cells. 


44 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 

Colonies  endophytic  in  gelatinous  envelope  of  other  algae. . 

A.  Nidulans  V.  Endophytica 

Colonies  not  endophytic. 

Cell  contents  grey  to  pale  blue-green,  never  bright  blue-green. 


Colonies  ovoid  to  spherical,  never  perforate A.  Nidulans 

Colonies  reticulate  to  clathrate A.  Clathrata 

Cell  contents  bright  blue-green. 

Cells  less  than  5 fx  broad A.  Staqnina 

Cells  more  than  5 /u  broad A.  Pbasina 


Aphanothece  clathrata  W.  & G.  S.  West.  PI.  6,  Fig.  3. 

Trans.  Roy.  Irish  Acad.  32,  Sec.  B:  111,  pi.  10,  /iffs.  9-11.  1906. 

Colonies  microscopic;  free-floating;  elongate  and  irregular  in  shape, 
usually  perforate  and  reticulate.  Gelatinous  colonial  envelope  hyaline 
and  homogeneous.  Cells  very  small,  bacilliform,  straight  or  curved, 
embedded  in  a solid  mass  in  the  colonial  envelope.  Cell  contents  homo- 
geneous, grey  to  light  blue-green.  (Euplanktont). 

Cells  0.6-1.0  fx  broad,  S.5-4.5  fx  long. 

Lindy  (r).  Little  Crooked  (sss),  Nancy  (ss),  Pokegama  (1)  (r),  Poor 
Farm  (rr).  Sand  (1)  (ss),  Wolf  (ss). 

Aphanothece  nidulans  P.  Richter.  PI.  6,  Fig.  1. 

Bot.  Not.  1884:  128.  1884. 

Colonies  spherical,  ovoid,  or  ‘‘nest-shaped^^;  enclosed  by  a homogene- 
ous, hyaline,  gelatinous  envelope.  Cells  broadly  cylindrical,  straight 
or  curved,  of  small  size  and  fairly  close  together.  Individual  sheaths 
of  cells  confluent  with  the  colonial  envelope.  Cell  contents  homogene- 
ous, grey  to  light  blue-green.  (Facultative  Planktont). 

Cells  1. 0-1.5  fx  broad,  up  to  3.5  [x  long. 

Beaver  (2)  (ss).  Deer  (ss).  Lower  McKenzie  (sss),  Pokegama  (sss).  Ten- 
derfoot (r). 

Certain  species  of  this  genus  resemble  bacterial  colonies  in  much  the 
same  manner  as  the  minute-celled  species  of  Aphanooapsa.  Here  again 
the  color  of  the  cell  contents  is  good  evidence  of  the  algal  nature  of  the 
organism. 


var.  endophytica  W.  & G.  S.  West.  PI.  5,  Fig.  6. 

Jour.  Linn.  Soc.  Bot.  40:  432,  pi.  19,  fig.  14.  1912. 

Cells  embedded  in  gelatinous  envelope  of  other  colonial  Myxophy- 
ceae.  Gelatinous  envelope  of  colony  confluent  with  envelope  of  host 


WISCONSIN  PHYTOPLANKTON 


45 


colony.  Cells  narrow,  at  least  twice  as  long  as  they  are  broad.  Cell 
contents  homogeneous;  generally  light  blue-green,  rarely  grey.  (Eu- 
planktont). 

Cells  0.8-1.5  fi  broad,  2.5-4.5  fi  long. 

Endophytic  in  sheaths  of  Coelosphaerium  Kuetzingianum  and  Micro- 
Cystis  aeruginosa, 

Birch  Island  (r),  Chetac  (ss),  Hound  (3)  (rr). 

Aphanothece  prasina  a.  Braun.  PI.  5,  Fig.  5. 

In  Rabenhorst,  Flora  Eur.  Algarum  2:  65.  1865;  Cooke,  Brit.  Fresh w.  Algae, 
218,  vl.  88,  Ms.  3a-3b.  1884. 

Colonies  spherical  to  cylindrical,  reaching  a diameter  of  3-4  cm.  un- 
der favorable  conditions;  bright  green  in  color.  Cells  evenly  dis- 
tributed throughout  the  colony,  broadly  cylindrical  and  with  rounded 
ends.  Individual  cell  sheaths  confluent  with  the  colonial  envelope. 
Cell  contents  homogeneous,  bright  blue-green.  (Tychoplanktont). 

Cells  5-6.5  broad,  7.7-11  /a  long. 

Beaverdam  (r),  Nancy  (rr),  Pokegama  (1)  (rrr). 

The  determination  of  this  and  the  following  species  is  open  to  ques- 
tion since  specific  differences  in  these  species  are  based  in  part  upon 
the  macroscopic  appearance  of  the  colony  when  growing  attached  to 
the  substratum.  The  determination  of  plankton  species  is  from  imma- 
ture colonies  and  must  rest  upon  cell  shape,  size,  and  color. 

Aphanothece  stagnina  (Sprengel)  A.  Braun.  PI.  6,  Fig.  2. 

in  Rabenhorst,  Algen  No.  1572;  Cooke,  Brit.  Fresh w.  Algae  219,  pZ.  88, 
fig.  4.  1884. 

Colony  spherical,  ellipsoidal,  or  cylindrical;  generally  macroscopic, 
0.5-20  mm  in  diameter,  pale  verdigris-green.  Cells  broadly  cylindrical, 
their  length  never  more  than  II/2  times  their  breadth.  Individual 
sheaths  of  cells  confluent  with  the  hyaline,  homogeneous,  gelatinous, 
colonial  envelope.  Cell  contents  homogeneous;  pale  to  bright  blue- 
green.  ( Tychoplanktont) . 

Cells  3-5  p,  broad ; 5-8  fx  long. 

Lake  of  the  Woods  (rr),  Whitefish  (rr). 

GLOEOTHECE  Nageli  1849. 

Colonies  free-floating  or  sessile,  of  comparatively  few  cells  enclosed 
by  a hyaline  or  variously  colored,  homogeneous,  gelatinous  envelope. 
Individual  sheaths  of  cells  prominent,  homogeneous  or  slightly  lamel- 


46 


WISCONSIN  PHYTOPLANKTON 


lated,  sometimes  2-8  cells  enclosed  by  a single  sheath.  Cells  elongate 
to  broadly  cylindrical,  with  rounded  ends  and  irregularly  distributed 
throughout  the  colonial  envelope  or  with  their  longer  axes  pointing  in 
the  same  general  direction.  Cell  contents  homogeneous  or  finely  granu- 
lose ; grey,  pale  to  bright  blue-green,  or  olive  green  in  color. 

Keproduction  by  vegetative  division  of  cells  at  right  angles  to  their 
long  axes. 

Gloeothece  linearis  Nageli.  PI.  6,  Fig.  5. 

Gatt.  einz.  Algen  58,  pi.  1,  fig.  G*.  1849. 

Colonies  small;  dull  yellow  to  flesh  color  or  dirty  olive-green;  en- 
closed by  a broad,  hyaline,  homogeneous,  gelatinous  envelope.  Cells 
elongate-cylindrical,  straight  or  arcuate,  with  rounded  ends.  Sheaths 
containing  one  cell  only,  broad,  hyaline,  having  the  same  general  out- 
line as  the  cell.  Cell  contents  homogeneous ; pale  to  bright  blue-green. 
(Tychoplanktont) . 

Cells  (without  sheath)  1.3-2. 5 /a  broad,  10.5-18  (x  long;  (with  sheath) 
4r-6  fi  broad,  13-22  jx  long. 

Harris  (r),  Muskallonge  (rr). 

var.  composita  var.  nov.  PI.  6,  Fig.  6. 

Cells  shorter  and  2-8  enclosed  by  a single,  broad,  firm,  homogeneous 
sheath.  Individual  sheaths  of  single  cells  or  groups  of  cells  not  con- 
fluent with  the  colonial  envelope.  (Tychoplanktont). 

Cells  (without  sheath)  3.0-3.5  fx  broad,  4-8  fx  long;  sheaths  10-12 
fx  broad,  20-35  fx  long. 

Deer  (rrr). 

RHABDODERMA  Schmidle  and  Lauterborn.  1900. 

Colonies  free-floating,  small,  of  comparatively  few  cells  enclosed  by  a 
hyaline,  homogeneous,  gelatinous  envelope.  Cells  cylindrical,  with 
rounded  apices,  straight  or  arcuate;  with  their  long  axes  pointing  in 
the  same  general  direction.  Individual  sheaths  of  cells  confluent  with 
colonial  envelope.  Cell  contents  homogeneous;  grey  to  bright  blue- 
green  in  color. 

Reproduction  by  vegetative  division  of  cells,  the  divisions  taking 
place  at  right  angles  to  the  long  axes  of  the  cells. 


WISCONSIN  PHYTOPLANKTON 


47 


Ehabdoderma  lineare  Schmidle  and  Lauterborn.  PI.  6,  Fig.  4. 
Ber.  d.  D.  Bot.  Ges.  18:  148,  pi.  6,  figs.  8-11.  1900. 

Specific  characters  as  those  of  the  genns.  (Euplanktont). 

Cells  2-3  IX  broad,  6-12  [x  long. 

Sand  (2)  (rrr),  Whitefish  (rr). 

This  genus  is  closely  related  to  Gloeothece,  the  chief  difference  being 
a lack  of  individual  sheaths  around  the  cells. 

DACTYLOCOCCOPSIS  Hansgirg  1888. 

Colonies  microscopic,  free-floating  or  lying  among  other  algae;  em- 
bedded in  a copious,  hyaline,  homogeneous,  acicular  to  fusiform,  gela- 
tinous envelope.  Cells  elongate,  acicular  and  with  pointed  ends; 
straight  arcuate,  sigmoid,  or  spirally  twisted  around  one  another.  In- 
dividual cell  sheaths  confluent  with  colonial  envelope.  Cell  contents 
homogeneous  or  with  the  color  bearing  area  localized  in  a definite  part 
of  the  cell ; grey  to  bright  blue-green  in  color. 

Reproduction  by  vegetative  division  of  cells  at  right  angles  to  their 
long  axes. 


KEY  TO  THE  SPECIES. 

Length  of  cells  never  more  than  sixteen  times  the  breadth, 

cells  frequently  bent D.  Raphidioides 

Length  of  cells  at  least  twenty  times  the  breadth,  cells  al- 
ways straight  D.  Acicularis 

Dactylococcopsis  rhaphidioides  Hansgirg.  PI.  6,  Pig.  7. 

Prodr.  d.  Algenfl.  v.  Bohmen  139,  fig.  49a.  1892;  Lemmermann,  Kryptogamenfl. 

d.  Mark  Brandenburg  3,  Algen  1:  50.  1907. 

Colonies  containing  2-8  or  more  cells.  Cells  fusiform ; straight,  arcu- 
ate or  sigmoid ; frequently  in  pairs  with  one  end  rounded  and  the  other 
pointed.  Colonies  enclosed  by  a copious,  hyaline,  homogeneous  en- 
velope. Cell  contents  homogeneous,  pale  blue-green.  (Facultative 
Planktont) . 

Cells  1-3  IX  broad,  5-25  ix  long. 

Deer  (sss).  Long  (2)  (rrr),  Mercer  (rr),  Reserve  (rr).  Rice  (1)  (rr). 

Hansgirg  gives  eight  as  the  maximal  number  of  cells  found  in  the 
colony  but  I have  observed  colonies  in  which  there  are  as  many  as  a 


48 


WISCONSIN  PHYTOPLANKTON 


hundred  cells.  These  cells  are  also  proportionally  longer  than  he  statei 
and  may  be,  in  extreme  cases,  sixteen  times  as  long  as  they  are  broad. 
In  this  respect  they  follow  the  cell  dimensions  delimited  ,by  Lemmer- 
mann. 

Dactylococcopsis  acicularis  Lemmermann.  PI.  6,  Figs.  8-10. 

Ber.  d.  D.  Bot.  Ges.  18:  309.  1900;  Kryptogamenfl.  d.  Mark  Brandenburg  3, 
Algen  1:  51,  44,  iig.  5.  1907. 

Cells  solitary  or  in  colonies  enclosed  by  a wide,  hyaline,  homogeneous, 
gelatinous  sheath.  Cells  elongate,  acicular,  with  poles  attenuated  to 
fine  points;  straight  or  slightly  arcuate.  Cell  contents  homogeneous 
and  pale  blue-green ; or  with  color  bearing  region  restricted  to  one  side 
of  cell.  (Euplanktont). 

Cells  2-2.5  fi  broad,  55-80  /x  long. 

Browns  (cc). 

The  localization  of  the  color  bearing  portion  at  one  side  of  the  cell  is 
quite  abnormal  for  a member  of  the  Myxophyceae,  but,  as  I have  stated 
elsewhere  (Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  620.  1918)  not- 
withstanding this  fact  the  alga  belongs  to  the  Myxophyceae. 


Order  HORMOGONEALES. 

Cells  always  in  filaments  that  generally  contain  a number  of  cells. 
Filaments  simple  or  branched ; solitary  or  united  to  form  definitely  or 
indefinitely  shaped  aggregates.  Free-floating,  sessile,  epiphytic,  or  en- 
dophytic. Cells  serially  arranged  to  form  trichomes,  which  when  en- 
closed by  a sheath  are  known  as  filaments.  Trichomes  either  the  same 
thickness  throughout,  attenuated  towards  both  extremities,  or  attenu- 
ated from  base  to  apex ; straight,  arcuate,  spirally  or  irregularly  twisted. 
Sheaths  of  filaments  tough  and  leathery;  or  gelatinous,  homogeneous 
to  lamellated,  hyaline  to  variously  colored,  and  distinct  or  confluent 
with  the  colonial  envelope.  Cell  shape  various.  Cell  contents  homo- 
geneous, or  with  numerous  pseudovacuoles;  grey,  light  to  dark  blue- 
green,  olive-green,  reddish-green,  ochraceo.us,  orange,  violet,  or  black 
in  color. 

Reproduction,  aside  from  vegetative  cell  division,  by  hormogones  and 
resting  spores. 


WISCONSIN  PHYTOPLANKTON 


49 


KEY  TO  THE  FAMILIES. 


Trichomes  without  heterocysts* Osciuatobiaceae 

Trichomes  with  heterocysts. 

Trichomes  not  attenuated  Nostocaceae 

Trichomes  attenuated  to  a hair-like  point Kivulariaceae 


Family  OSCILLATORIACEAE. 

Trichomes  free-floating,  sessile,  epiphytic,  or  endophytic;  of  one  or 
mere  cells  forming  simple  or  branched  filaments  with  one  or  more  tri- 
chomes within  a single  sheath.  Sheaths  of  various  forms;  copious, 
gelatinous,  hyaline  or  colored,  homogeneous  to  lamellated;  firm,  nar- 
row and  homogeneous  or  lamellated;  or  entirely  lacking.  Filaments 
straight  or  spirally  twisted.  Cells  disciform,  cylindrical,  or  barrel- 
shaped.  Apical  cell  of  trichomes  frequently  conical  and  capitate. 
Heterocysts  never  present  in  the  trichomes.  Cell  contents  homogene- 
ous, granulose,  or  with  pseudovacuoles ; variously  colored. 

Reproduction  by  vegetative  division  of  cells  and  the  formation  of 
liormogones. 


KEY  TO  THE  GENERA. 

Trichomes  solitary  or  in  flocculent,  readily  dissociating  masses. 


Trichomes  containing  but  one  cell Spiruuna 

Trichomes  containing  more  than  one  cell. 

Sheaths  of  filaments  firm,  generally  projecting  beyond 

the  trichome Lyngbya 

Sheaths  delicate  or  lacking,  not  projecting  beyond 

trichome  Oscillatoria 

Trichomes  laterally  united  to  form  free-floating  bundles  which 

do  not  dissociate  readily  Trichodesmiiim 


SPIRULINA  Turpin  1827. 

Trichome  consisting  of  a single,  elongate,  cylindrical  cell  that  is  not 
attenuated  but  with  rounded  ends.  Filaments  without  sheaths  and 
twisted  to  form  loose  or  compact  regular  spirals.  Cell  contents  homo- 
geneous or  granulose ; light  to  dark  blue-green  in  color. 

Reproduction  by  vegetative  division  of  cells  at  right  angles  to  the 
long  axis.  No  hormogone  formation  possible. 

*Cells  commonly  larger  than  the  vegetative  cells  and  with  heavy  walls  that 
have  a conspicuous  nodule  at  each  pole.  Cell  contents  a homogeneous,  pellucid, 
non-cytoplasmic  substance. 


4 


50 


WI8C02^SIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 


Turns  of  spirals  not  over  5 fji  in  diameter S.  Majob 

Turns  of  spirals  over  10  fx  in  diameter S.  Pbinceps 


Spirulina  major  Kiitzing.  PI.  7,  Fig.  1. 

Phycol.  generalis  183.  1843;  Gomont,  Ann.  Sci.  Nat.  7 Ser.,  Bot.  16:  251,  pi.  7, 
fig.  29.  1892. 

Filaments  free-floating  and  solitary,  or  forming  a greenish  scum. 
Trichomes  in  a more  or  less  loose  spiral  that  is  straight  or  bent.  Cell 
contents  homogeneous ; bright  blue-green.  Sheath  of  filament  lacking. 
( Tychoplanktont) . 

Trichomes  1.2-1. 7 fx  in  diameter.  Spirals  2.5-4  p.  broad,  2.7-5 
fx  betv/een  turns. 

White  Ash  (rrr). 

Spirulina  princeps  (W.  & G.  S.  West)  G.  S.  West  emend.  PI.  7,  Pig.  2. 

Jour.  Linn.  Soc.  Bot.  38:  179,  pi.  9,  fig.  5.  1907;  W.  & G.  S.  West,  Trans.  Linn. 
Soc.  Bot.  2 iSer.,  Bot.  6:  205.  1902. 

Trichomes  solitary,  in  loose  spirals  that  may  be  straight  or  curved. 
Ends  of  trichomes  blunt  or  rounded.  Cell  contents  homogeneous  or 
with  a few  scattered  granules;  bright  blue-green.  (Tychoplanktont). 

Trichomes  3-5  fx  broad.  Spirals  8.8-16  [x  broad,  9.5-12  fx  between 
turns. 

Poor  Farm  (rrr). 

OSCILLATORIA  Vaucher  1803. 

Trichomes  possessing  a peculiar  power  of  spontaneous  movement  of 
an  oscillating,  rolling,  or  gliding  type;  free-floating;  solitary  or  in 
flocculcnt  masses ; sometimes  forming  strata  in  moist  places.  Trichomes 
unbranched,  cylindrical,  entirely  without  or  Avith  barely  perceptible 
sheaths.  Ends  of  trichomes  straight,  slightly  attenuated,  but  never  at- 
tenuated to  a point.  Terminal  cells  rounded  or  ealyptrate.  Cell  shape 
cylindrical  to  disciform.  Cell  contents  usually  homogeneous  or  granu- 
lose,  rarely  with  pseudovacuoles.  Color  of  cells  variable. 

Reproduction  by  hormogones. 


WISCONSIN  PHYTOPLANKTON 


51 


KEY  TO  THE  SPECIES. 

Apex  of  trichome  gradually  tapering 
Apex  of  trichome  not  tapering 

OsciLLATORiA  PROLiFiCA  (Greviile)  Gomont.  PI.  7,  Figs.  3-5. 

Ann.  Sci.  Nat.  7 Ser.  Bot.  16:  205,  pi.  6,  fig.  8.  1892;  Olive,  Trans.  Wis.  Acad. 
Sei.,  Arts,  & Lett.  15":  124-134.  1905;  Hyams  and  Richards,  Technology  Quart. 

14:  302-310,  figs.  1-8.  1901. 

Filaments  rarely  solitary,  generally  irregularly  matted  to  form  free- 
tioating  flocculent  masses.  Plant  masses  blood-red  to  dirty  purple,  be- 
coming lilac  when  dried.  Trichomes  straight,  elongate,  not  constricted 
at  cross  walls  of  cells,  and  slightly  tapered  at  apex  with  the  terminal 
cell  of  mature  trichomes  obtuse-capitate.  Cells  cylindrical,  slightly 
longer  than  they  are  broad.  Cell  contents  with  numerous  reddish 
pseudovacuoles,  sometimes  with  rows  of  granules  at  the  cross  walls. 
(Euplanktont). 

Cells  2.2-5  fx  broad,  4-6  [x  long. 

Geneva  (aa).  Pine  (1)  (aa). 

This  species  is  closely  related  to  0.  ruhescens  D.  C.,  but  if  GomonCs 
monograph  of  the  Oscillatoriaceae  must  be  taken  as  the  starting  point 
for  nomenclature  of  the  group  the  two  are  distinct.  Both  species  are 
peculiar  in  that  they  produce  blooms  in  lakes  at  a time  when  the  water 
is  very  cold  or  covered  with  ice.  The  masses  of  filaments  do  not  have 
the  usual  yellowish-green  color  but  are  blood  red  to  dirty  purple  and 
the  phenomenon  is  spoken  of  in  Europe  as  ‘‘bloody’^  or  ‘‘Burgundy” 
bloom. 

Olive  has  described  the  occurrence  of  such  a bloom  in  Pine  lake  of 
this  state  and  discussed  the  literature  of  the  subject.  The  alga  also 
appeared  in  profusion  in  Lake  Geneva  this  (1918)  spring  at  the  time 
w'hen  the  ice  was  beginning  to  disappear.  It  was  not  frozen  in  the  ice 
but  grew  luxuriantly  in  the  water  below  the  ice  and  gave  a deep  red- 
dish color  that  was  especially  noticeable  in  the  cracks  between  the  ice. 
The  alga  had  not  been  noted  in  the  lake  before  this  time  and  its  sporadic 
appearance  is  quite  like  the  sporadic  appearance  of  0.  ruhescens  in  the 
Swiss  lakes.  The  excessive  growth  of  0.  prolifica  is  not  wholly  corre- 
lated with  cold  water  since  it  has  remained  present  throughout  the 
summer,  but  not  in  such  quantities  as  early  in  the  spring.  This  abund- 
ant growth  of  the  alga  in  the  summer  has  also  been  noted  in  a Massa- 
chusetts lake  by  Hyams  and  Richards  and  furnishes  a physiological  as 
well  as  a morphological  distinction  between  0.  prolifica  and  0.  ruhes- 
cens. 


O.  Prolifica 
. . .0.  Tenuis 


52 


WISCONSIN  PHYTOPLANKTON 


OsciLLATORiA  TENUIS  C.  A.  Agardh.  PI.  7,  Fig.  6. 

Algarum  decades  2:  25.  1813;  Gomont,  Ann.  Sci.  Nat.  7 S§r.  Bot.  16:  220, 
j)J.  7,  iigs.  2-3.  1832. 

Filaments  solitary  or  in  floceose  masses  that  are  pale  blue-green  in 
color.  Trichomes  straight,  slightly  constricted  at  the  cross  walls.  Termi- 
nal cells  the  same  diameter  as  those  in  the  median  portion  of  the  trich- 
ome,  straight  or  curved;  apical  cells  rounded  but  not  capitate.  Cell 
shape  disciform.  Cell  contents  homogeneous  except  for  a row  of  gran- 
ules along  the  cross  walls.  (Tychoplanktont) . 

Cells  4—10  broad,  2.6-5  long. 

Monona  (rr). 

var.  TERGESTiNA  (Kutzing)  Rabenhorst.  PI.  7,  Figs.  7-8. 

Flora  Eur.  Algarum  2:  102.  1865. 

Trichomes  narrower  than  the  foregoing.  (Tychoplanktont). 

Cells  4-6  fx  broad. 

Geneva  (ss). 

LYNGBYA  C.  A.  Agardh.  1824. 

Filaments  solitary  or  interwoven  to  form  floceose  masses;  free-float- 
ing or  in  an  expanded  stratum.  Sheaths  of  filaments  narrow,  firm, 
hyaline  or  colored,  homogeneous  or  lamellated,  generally  projecting 
for  some  distance  beyond  the  trichome.  Filaments  unbranched,  cylin- 
drical ; straight,  flexed,  or  twisted  into  regular  spirals.  Triciiomes  gen- 
erally the  same  thickness  throughout,  rarely  slightly  attenuated  at  the 
apices ; sometimes  constricted  at  the  cross  walls.  Apical  cell  with  distal 
end  rounded  or  slightly  capitate.  Cell  contents  homogeneous,  granu- 
lose,  or  with  numerous  pseudovacuoles ; grey,  pale  to  bright  blue-green 
or  variously  colored. 

Reproduction  by  the  formation  of  hormogones. 

KEY  TO  THE  SPECIES. 

Filaments  not  over  4 /a  in  thickness,  with  pale  hlue-green  to  grey  cell  contents. 


Filaments  straight L.  Limnetica 

Filaments  in  regularly  coiled  spirals L.  Contorta 

Filaments  over  10  ti  in  diameter,  contents  deeply  colored L.  Bibgei 


Lyngbya  limnetica  Lemmermann.  PI.  7,  Figs.  9-11. 

Bot.  Cent.  76:  154.  1898;  Kryptogamenfl.  d.  Mark  Brandenburg  3,  Algen  1: 
135,  102,  fig.  8.  1907. 

Filaments  free-floating,  generally  solitary ; straight  or  slightly  flexed. 
Trichomes  not  constricted  at  the  cross  walls.  Apical  cells  the  same 


WISCONSIN  PHYTOPLANKTON 


53 


thickness  as  the  other  cells,  with  distal  end  rounded  but  not  capitate. 
Sheaths  firm,  hyaline,  very  narrow,  extending  for  some  distance  beyond 
the  end  of  the  trichome.  Cells  cylindrical,  at  least  twice  as  long  as 
broad.  Cell  contents  homogeneous;  generally  grey,  rarely  blue-green 
in  color.  (Euplanktont). 

Cells  1-1.5  fi  broad,  3-8  /a  long. 

Bear  (1)  (c),  Geneva  (ss),  Soft  (rr),  Upper  Nashotah  (rrr). 

The  length  of  the  individual  cells  of  Wisconsin  specimens  exceeds 
that  given  by  Lemmermann  but  it  is  very  probable  that  I am  dealing 
with  the  same  species  that  he  names  L.  limnetica.  Several  plankton 
“species’^  have  been  described  which  are  closely  related  and  it  is  very 
probable  that  future  investigations  will  show  that  all  of  these  straight, 
very  narrow,  colorless  ‘‘species”  should  be  included  under  one  collect- 
ive specific  name. 

Lyngbya  contorta  Lemmermann.  PI.  7,  Figs.  12-13. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  6:  202,  pi.  5,  -figs.  10-13.  1898;  G.  S. 
West  Jour,  of  Bot.  47:  246,  pi.  498,  iigs.  5^-5g.  1909. 

Filaments  free-floating,  solitary ; occasionally  straight,  generally 
twisted  to  form  regular,  loose  or  compact  spirals  or  helices.  Sheaths 
firm,  very  thin,  extending  for  some  distance  beyond  the  trichomes.  Trich- 
omes  the  same  thickness  throughout,  not  constricted  at  the  cross  walls, 
apical  cells  rounded  but  not  capitate  at  the  distal  ends.  Cell  contents 
homogeneous,  grey  to  pale  blue-green.  (Euplanktont). 

Cells  1.5-2  fi  broad,  3-6  /a  long.  Spirals  15-20  /a  broad,  6-14  fi  be- 
tween the  turns. 

Mendota  (rr).  Pine  Tree  (ss).  Poor  Farm  (s).  White  Ash  (cc). 

The  specific  distinction  of  this  species  is  based  in  large  part  upon  the 
spiral  twisting  of  the  filament.  Since  certain  normally  straight  fila- 
ments of  other  algae  become  spirally  twisted  under  limnetic  conditions 
(vide  W.  & G.  S.  West,  Proc.  Roy.  Soc.  London  Ser.  B,  81:  169,  fig.  1. 
1909)  the  validity  of  spiral  twisting  as  a specific  character  arises. 
L.  contorta  was  found  in  considerable  quantity  at  different  stations  and 
the  vast  majority  of  filaments  were  spirally  twisted.  On  the  other 
hand  numerous  filaments  with  cells  of  the  same  size  that  showed  no 
signs  of  twisting  were  collected  from  other  stations.  I think  that  Lem- 
mermann is  correct  in  considering  these  distinct  species  and  that  the 
spiral  twisting  of  filaments  in  plankton  species  of  the  Myxophyceae  is 
a sufficiently  constant  character  to  warrant  the  establishment  of  species 
in  both  this  genus  and  Anahaena. 


54 


WISCONSIN  PHYTOPLANKTON 


Lyngbya  birgei  G.  M.  Smith.  PI.  7,  Figs.  14-15. 

Bull.  Torr.  Bot.  Cl.  43:  482,  pi.  26,  -fig.  28.  1916. 

Filaments  free-floating,  solitary,  never  forming  floccose  masses; 
straight  or  slightly  flexed.  Sheaths  firm,  at  times  of  considerable  thick- 
ness, hyaline,  generally  homogeneous,  rarely  lamellated,  extending  for 
some  distance  beyond  the  trichome.  Trichomes  not  attenuated  at  apices 
and  without  constrictions  at  the  cross  walls.  Terminal  cells  rounded 
but  not  capitate  at  distal  ends.  Cell  shape  disciform.  Cell  contents 
rarely  homogeneous  and  with  grey  to  olive  green  contents ; usually  with 
numerous  pseudovacuoles.  (Euplanktont). 

Cells  18-23  fx.  broad,  2-5.5  long.  Sheaths  .5-4  p.  thick. 

Balsam  (rr).  Bear  Trap  (cc).  Big  (cc).  Deer  (rrr),  Elizabetti  (ss),  Fowler 
(rrr).  Half  Moon  (c),  Kegonsa  (aa).  Lac  la  Belle  (rr).  Little  Crooked  (r), 
Little  Wood  (rr),  Loveless  (rr).  Lower  Nashotah  (rr),  Mary  (ss),  Mendota 
(cc),  Mercer  (rr),  Monona  (cc),  Mudhen  (rr),  Nagawicka  (rr),  Oconomowoc 
(rr).  Pope  (rrr).  Round  (3)  (sss).  Sand  (1)  (r).  Spirit  (sss),  Squirrel  (sss), 
Upper  Nashotah  (cc).  Upper  Turtle  (rr),  V/apagossett  (cc),  Waubesa  (cc), 
Wolf  (r). 

This  is  undoubtedly  the  alga  that  Trelease  (Trans.  Wis.  Acad.  Sci., 
Arts,  & Lett.  7:  124,  pi.  10,  fig.  6.  1888)  reported  from  Lake  Mendota 
as  Lyngbya  Wollei  Farlow.  L.  Viollei  has  been  shown  to  be  a Fleet o- 
nema  (P.  Wollei  Farlow)  and  Trelease ’s  determination  is  undoubtedly 
a mistake. 


TRICHODESMIUM  Ehrenberg  1830. 

Trichomes  laterally  joined  to  form  spindle-  to  scale-shaped,  free- 
floating  colonies  that  are  not  enclosed  by  a gelatinous  sheath.  Trichomes 
cylindrical,  straight  or  spirally  twisted,  of  the  same  thickness  through- 
out or  with  apices  slightly  attenuated.  Apical  cell  undifferentiated, 
or  rounded  and  slightly  capitate.  Sheaths  of  trichomes  very  delicate. 
Cells  disciform  to  barrel-shaped.  Cell  contents  homogeneous,  granu- 
lose,  or  with  numerous  pseudovacuoles.  Heterocysts  and  resting  spores 
lacking. 

Reproduction  by  the  formation  of  hormogones. 

i RicHODESMiUM  LACUSTRE  Klebahn.  PI.  8,  Pig.  1. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  3:  13.  1895;  Flora  80:  271,  pi.  4,  iigs. 
31-33.  1895. 

Trichomes  laterally  joined  to  form  plate-like,  free-floating  masses 
that  are  not  enclosed  by  a gelatinous  envelope.  Filaments  with  a very 
delicate,  homogeneous  sheath.  Trichomes  straight,  not  attenuated  at 
the  apices,  and  with  terminal  cells  rounded  but  not  capitate.  Cells 


WISCONSIN  PHYTOPLANKTON 


55 


disciform,  with  straight  or  markedly  convex  sides.  Cell  contents  occa- 
sionally homogeneons  and  pale  to  bright  bine-green  in  color ; generally 
with  numerous  pseudovacuoles.  Trichomes  without  heterocysts  or 
spores.  (Euplanktont). 

Cells  5-7  II  broad,  5-7  ix.  long.  Colonies  up  to  1 mm.  in  length. 

Amicoy  (rrr),  Beaverdam  (r),  Island  (rr),  Lake  of  the  Woods  (rrr),  Little 
Bass  (1)  (rr),Mud  (1)  (s),  Nicaboyne  (rr),Bice  (1)  (rr),Wild  Goose  (rrr). 

The  general  appearance  of  the  colony  at  once  suggests  an  ApJianizo- 
menon  species  with  cells  shorter  and  more  rounded  than  the  familiar 
A.  flos-aquae.  I have  examined  a sufficient  number  of  colonies  to  feel 
confident  in  confirming  Klebahn’s  statement  that  there  are  no  spores 
or  heterocysts  in  the  alga  under  consideration.  This  being  the  case  it 
is  impossible  to  refer  the  species  to  AphanizomenoUj  but  it  should  be 
considered  a freshwater  species  of  the  common  Tricliodesmium  of  tropi- 
cal seas. 


Family  NOSTOCACEAE. 

Filaments  free-floating,  sessile,  epiphytic,  or  endophytic;  solitary  or 
in  colonies  of  microscopic  to  macroscopic  size  that  are  definitely  or  in- 
definitely shaped.  Trichomes  always  unbranched ; straight,  flexed,  spi- 
rally twisted,  or  irregularly  interwoven.  Sheath  rarely  firm  and  nar- 
row; generally  copious,  gelatinous,  hyaline  or  colored,  and  distinct  or 
confluent  with  the  colonial  envelope.  Trichomes  generally  the  same 
thickness  throughout  and  with  spherical  to  cylindrical  cells.  Hetero- 
cysts either  terminal  or  intercalary,  solitary  or  catenate.  Resting 
spores  variously  shaped,  adjacent  to  or  remote  from  the  heterocysts; 
formed  in  all  genera.  Cell  contents  homogeneous,  granulose,  or  with 
pseudovacuoles ; grey  or  variously  colored. 

Reproduction  by  fragmentation  of  colony,  hormogones,  and  resting 
spores. 

KEY  TO  THE  GENERA. 

Trichomes  solitary  or  interwoven  to  form  flocculent  masses  of 

small  size Anabaena 

Trichomes  laterally  joined  to  form  small  plate-like  colonies Aphanizomenon 

ANABAENA  Bory  1822. 

Filaments  free-floating  or  forming  a delicate  mucous  layer;  solitary 
or  in  floccose  colonies.  Trichomes  the  same  thickness  throughout  or 
slightly  attenuated  at  the  apices;  straight,  spiral,  circinate,  or  aggre- 
gated without  deflnite  order.  Sheaths  delicate  or  copious,  gelatinous, 
hyaline,  homogeneous,  rarely  confluent  with  the  colonial  envelope ; some- 


56 


WISCONSIN  PHYTOPLANKTON 


times  entirely  lacking.  Cells  spherical  to  barrel-shaped,  rarely  cylindri- 
cal, never  disciform.  Heterocysts  approximately  spherical,  always  in- 
tercalary, generally  solitary  and  with  several  in  a filament.  Spores 
variously  shaped,  contiguous  to  or  remote  from  heterocysts,  solitary  or 
in  short  catenate  series.  Cell  contents  homogeneous,  granulose,  or  with 
numerous  pseudovacuoles;  grey,  blue-green,  or  variously  colored. 

Reproduction  by  hormogones  and  spores. 

KEY  TO  THE  SPECIES. 

Filaments  straight  or  slightly  curved. 

Spores  spherical A.  Planctoxica 

Spores  longer  than  they  are  broad. 

Length  of  spores  not  over  twice  their  breadth. 

Breadth  of  spores  less  than  twice  that  of  vegetative  cells. 


Spores  oval  to  elliptic  in  optical  cross  section. 

Vegetative  cells  less  than  8 ^ broad A.  Arrmis 

Vegetative  cells  over  10  ii  broad A.  Limwetica 

Spores  hexagonal  in  optical  cross  section A.  Macrospora 

Breadth  of  spores  more  than  twice  the  vegetative  cells A.  Levanderi 

Length  of  spores  at  least  three  times  their  breadth A.  Bori^etiana 

Filaments  spirally,  circinately,  or  irregularly  twisted. 

Trichomes  solitary,  not  forming  floccose  masses. 

Curving  of  trichome  a definite  spiral A.  Spiro  ides 

Curving  of  trichome  not  a definite  spiral. 

Length  of  spore  at  least  four  times  breadth . . A.  Augstumalis  I.  C.  Marchia 

Length  of  spore  about  twice  the  breadth A.  Circinalis 

Trichomes  forming  a fioccose  mass. 

Spores  in  a mass  at  center  of  colony A.  Lemmermanni 

Spores  not  in  a mass  at  the  center  of  the  colony. 

Trichomes  loosely  associated,  individual  filaments  some- 
times in  spiral  turns A.  Circinalis 

Trichomes  greatly  and  irregularly  twisted  to  form  com- 
pact masses  A.  Flos-Aquab 


Anabaena  planctonica  Brunnthaler.  PI.  8,  Fig.  2. 

Sitzenbr.  d.  kais.  Ak.  d.  Wiss.  Wien  112,  Abt.  1;  292.  1903. 

Filaments  free-floating,  solitary,  straight,  or  slightly  bent.  Trichomes 
enclosed  by  a copious,  hyaline,  very  gelatinous  sheath.  Vegetative  cells 
spherical,  hemispherical,  or  broadly  elliptic.  Heterocysts  spherical. 
Spores  solitary,  remote  from  or  adjacent  to  heterocysts,  spherical  or 
slightly  elongate,  somewhat  broader  than  the  vegetative  cells.  Cell  con- 
tents rarely  homogeneous,  usually  with  numerous  pseudovacuoles.  (Eu- 
planktont). 

Vegetative  cells  9-15  fi  broad;  heterocysts  12-14  /a  broad;  spores 
12.5-20  /X  broad,  12.5-30  fx  long. 

Birch  (1)  (cc),  Center  (oc),  Cranberry  (cc).  Devils  (2)  (ss),  Rock  (cc). 


WISCONSIN  PHYTOPLANKTON 


57 


Many  juvenile  spores  of  other  species  are  spherical  but  the  spores  of 
this  species  never  become  appreciably  elongated. 

Anabaena  affinis  Lemmermann.  PL  8,  Fig.  7. 

Abh.  Nat.  Ver.  Bremen  14:  261,  pi.  1,  figs.  12-13,  16-17.  1897. 

Filaments  solitary,  free-floating,  straight  or  slightly  flexed;  with  a 
wide,  homogeneous,  hyaline,  faintly  discernible  gelatinous  envelope. 
Mature  vegetative  cells  generally  spherical;  rarely  with  homogeneous 
contents,  usually  with  pseudovacuoles.  Heterocysts  spherical.  Spores 
generally  remote  from  heterocysts,  short  or  elongate  cylindrical,  with 
rounded  ends  and  covered  with  a thick,  smooth  wall.  (Facultative 
planktont) . 

Cells  5-6  /t  broad ; heterocysts  7.5-10  (x  broad ; spores  9.5-12  ix  broad, 
17-26  fx  long. 

Llndy  (rr).  Lost  (rr).  North  Turtle  (c),  Pardee  (sss),  Poplar  (ss).  Sand 
(1)  (s). 


Anabaena  limnetica  G.  M.  Smith.  PI.  8,  Fig.  8. 

Bull.  Torr.  Bot.  Cl.  43:  481,  pi.  26,  fig.  27.  1916. 

Filaments  free-floating,  solitary,  straight  or  slightly  flexed;  with  a 
copious,  homogeneous,  hyaline  sheath.  Vegetative  cells  spherical  or 
with  poles  flattened.  Hdterocysts  spherical.  Spores  smooth-walled, 
solitary,  broadly  ovoid,  remote  from  or  adjacent  to  the  heterocysts.  Cell 
contents  rarely  homogeneous,  generally  with  numerous  pseudovacuoles. 
(Euplanktont). 

Cells  12-15  fx  broad ; heterocysts  10-14  fx  broad;  spores  17-20  fx  broad, 
20-30  fx  long. 

Bear  Trap  (ss),  Birch  (1)  (cc).  Soft  (ss).  Tamarack  (cc).  White  Ash  (ss). 

Anabaena  macrospora  var.  robust'a  Lemmermann.  PI.  8,  Fig.  6. 
Bot.  Cent.  76:  154.  1898. 

Filaments  solitary,  free-floating,  straight  or  slightly  bent,  frequently 
attaining  a considerable  length;  with  a copious,  hyaline,  homogeneous, 
gelatinous  envelope.  Mature  vegetative  cells  spherical  or  subspherical 
with  flattened  ends.  Heterocysts  spherical.  Spores  solitary  or  in  pairs, 
adjacent  to  or  remote  from  heterocysts,  cylindrical  with  conical  ends 
and  hexagonal  in  optical  cross  section.  Spore  wall  smooth  and  thick. 
Cells  containing  numerous  pseudovacuoles.  (Euplanktont). 

Cells  12-16  fx  broad,  9-12  ix  long;  heterocysts  12-16  fx  broad;  spores 
17-19  /A  broad,  30-34  fx  long. 

Camp  (cc).  Squirrel  (ss). 


58 


WISCONSIN  PHYTOPLANKTON 


Anabaena  Levanderi  Lenimermann.  PI.  8,  Figs.  4-5. 

Ber.  d.  D.  Bot.  Ges.  24:  536.  1906. 

Filaments  solitary,  free-floating,  straight  or  slightly  flexed,  not  en- 
closed by  a gelatinous  sheath.  Trichomes  cylindrical,  slightly  con- 
stricted at  the  cross  walls  of  the  cells.  Vegetative  cells  twice  as  long  as 
they  are  broad,  cylindrical,  with  rounded  ends.  Heterocysts  hyaline, 
spherical  or  ellipsoid.  Spores  solitary,  adjacent  to  or  remote  from  the 
lieterocysts,  twice  as  broad  as  the  vegetative  cells,  ellipsoid  in  shape. 
Cell  contents  rarely  homogeneous  and  pale  blue-green  to  grey ; usually 
with  numerous  pseudovacuoles.  (Euplanktont). 

Cells  4-6  IX,  broad,  11-33  [x,  long ; heteroeysts  6.5-8  broad,  6. 5-9. 5 /a 
long ; spores  8-15  /x  broad,  19-45  fi  long. 

Chain  (sss). 

The  dimensions  of  all  specimens  found  in  Chain  lake  have  been  near 
the  minimal  limits  set  by  Lemmermann. 

Anabaena  Bornetiana  Collins.  PI.  8,  Fig,  3. 

Erythrea4:  120.  1896. 

Filaments  free-floating,  straight  or  slightly  curved.  Vegetative  cells 
spherical  or  slightly  shorter  than  they  are  broad,  with  homogeneous 
pale  blue-green  contents.  Sheaths  of  trichomes  very  delicate.  Hetero- 
cysts spherical  to  elongate.  Spores  elongate  cylindrical,  with  rounded 
ends,  adjacent  to  and  on  both  sides  of,  or  remote  from  the  heterocysts. 

( Tychoplanktont) . 

Vegetative  cells  12  /x  broad;  heterocysts  13-14  /x  broad,  13-20  (x.  long; 
spores  15-20  /x  broad,  50-90  fx,  long. 

George  (rr). 

Only  a few  filaments  of  this  species  were  found  in  George  lake  and 
these  contained  but  few  spores  which  were  not  always  adjacent  to  the 
heterocysts.  The  species  may,  therefore,  not  be  A.  Bornetiana  for  Col- 
lins states  that  the  spores  are  always  adjacent  to  the  heterocysts. 

Anabaena  augstumalis  var.  marchica  Lemmermann.  PI.  8,  Figs.  9-10. 
Forschungsbr.  a.  d.  Biol.  Stat  zu  Plon  12:  147.  1905. 

Filaments  solitary,  free-floating,  more  or  less  bent  but  not  circinate, 
without  a gelatinous  envelope.  Vegetative  cells  spherical,  broadly  ellip- 
soid or  cylindrical ; with  numerous  pseudovacuoles.  Heterocysts  spheri- 
cal or  slightly  elongate.  Spores  remote  from  heteroeysts,  elongate  cylin- 


WISCONSIN  PHYTOPLANKTON 


59 


drical,  with,  rounded  ends.  Spore  wail  delicate,  smooth,  and  hyaline. 
(Facultative  planktont). 

Cells  5-7  fx  broad,  5-9.5  fx  long;  heterocysts  8-9.5  /x  broad,  8-14  tx 
long;  spores  9.5-12  jx  broad,  40-70  /x  long. 

Bone  (ss).  Center  (cc). 

Anabaena  spiroides  var.  crassa  Lemmermann.  PL  9,  Figs.  1-3. 

Bot.  Cent.  76:  155.  1898;  Kryptogamenfl.  d.  Mark.  Brandenburg  3,  Algen  1: 

]88,  159,  figs.  15-16.  1907. 

Filaments  solitary,  free-floating;  forming  a regular,  evenly  spaced 
spiral  enclosed  by  a very  transparent,  homogeneous,  gelatinous  envelope. 
Cells  spherical  or  with  flattened  ends.  Heterocysts  spherical,  hyaline 
or  pale  yellow.  Spores  solitary,  remote  from  the  heterocysts,  generally 
broadly  ovoid.  Cell  contents  rarely  homogeneous,  usually  with  numer- 
ous pseudovacuoles.  (Euplanktont). 

Cells  11-15  [X  broad ; heterocysts  10-17  fx  broad ; spores  20-25  [x  broad, 
27-42  (generally  27-31)  /x  long.  Spirals  50-60  /x  broad  and  45-55  /x 
between  turns. 

Big  Butternut  (cc),  Big  St.  Germain  (cc),  Granite  (cc).  Hooker  (c),  Ke- 
gonsa  (a).  Long  (2)  (sss),  Little  Butternut  (cc),  Mendota  (cc),  Monona  (aa). 
North  Twin  (sss).  Round  (3)  (ss),  South  Turtle  (c).  Vermilion  (ccc). 

Anabaena  circinalis  (Kutzing)Eabenhorst.  PI.  9,  Figs.  4-5. 

Algen  No.  209.  1852;  Phillips,  Grevillea  9:  5,  pi.  134,  figs.  e-g.  1880;  Bornet 

et  Flahault,  Ann.  Sci.  Nat.  7 Ser.  Bot.  7:  230.  1888. 

Anahaena  Hassallii  (Kiitzing)  Wittrock.  Bot.  Not.  1882:  58.  1882. 

Filaments  free-floating,  rarely  solitary,  curved  or  sigmoid;  usually 
greatly  and  irregularly  twisted  to  form  floccose  masses.  Filaments 
v/ith  or  without  a copious,  hyaline,  gelatinous  envelope.  Cells  spheri- 
cal or  appreciably  flattened  at  the  poles,  generally  with  numerous 
pseudovacuoles.  Heteroeysts  spherical  to  subspherical.  Spores  usu- 
ally remote  from  the  heterocysts,  cylindrical,  with  rounded  ends  when 
mature,  frequently  curved  and  with  smooth  walls.  (Euplanktont). 

Cells  8-14  /X  broad ; heterocysts  8-10  /x  broad ; spores  16-18  /x  broad, 
26-30  /X  long  when  mature. 

Center  (ss),  Chain  (sss).  Lac  la  Belle  (rr),  Mercer  (rr),  Nagawicka  (it). 
Pike  (r).  Upper  Nashotah  (rr),  Wapagossett  (sss),  Winnebago  (ss). 

This  species  differs  from  A.  flos-aquae  in  the  loose  looping  of  the 
trichomes,  the  larger  vegetative  cells  and  the  broader  spores. 


60 


WISCONSIN  PHYTOPLANKTON 


var.  MACROSPORA  (Wittrock)  de  Toni.  PI.  9,  Fig.  6;  PI.  10,  Fig.  1. 
Sylloge  algarum  5:  445.  1907. 

Anabaena  Hassallii  var.  macrospora  Wittrock,  Bot.  Not.  1882  : 59,  figs.  7-9. 
1882. 

Vegetative  cells  somewhat  smaller  but  with  much  narrower  and  pro- 
portionally longer  spores. 

Cells  7-8  /X  broad ; heterocysts  7.5-10  fx  broad ; spores  9-10.5  p.  broad, 
28-42  (i  long. 

Camp  (sss). 

Anabaena  flos-aquae  (Lyngbye)  de  Brebisson.  PI.  10,  Figs.  2-4. 

Mem.  de  la  soc.  Acad,  de  Falaise  1835:  36.  1836;  Kiitzing,  Tabulae  Phycol.  1: 
51,  pi.  94,  fig.  4.  1848;  Bornet  et  Flahault,  Ann.  Sci.  Nat.  7 Ser.  Bot.  7;  228. 

1888. 

Filaments  free-floating,  densely  coiled,  irregularly  twisted  and  inter- 
woven to  form  a floccose  colony.  Cells  spherical  or  cylindrical  with 
convex  sides ; generally  containing  numerous  pseudovacuoles.  Hetero- 
cysts broader  and  longer  than  the  vegetative  cells.  Spores  cylindrical, 
with  rounded  ends,  usually  curved,  solitary  or  in  short  catenulate 
series ; generally  adjacent  to,  rarely  remote  from  the  heterocysts.  (Eu- 
planktont) . 

Vegetative  cells  4-8  (generally  5.5)  /x  broad;  heterocysts  6-9  /x  broad; 
spores  7-13  /x  broad,  20-50  /x  long. 

Bear  (1)  (cc),  Birch  Island  (r).  Browns  (cc).  Camp  (ss).  Catfish  (ss), 
Catherine  (rr),  Cochrane  (sss).  Crab  (r),  Crawling  Stone  (rrr).  Crooked  (sss), 
Des  Moines  (rr).  Devils  (1)  (r).  Eagle  (sss),  Fish  (rr).  Grassy  (r).  Green 
(2)  (sss).  Half  Moon  (rr).  Hooker  (r).  Horse  (rrr),  Jag  (rr),  Jennie  (ss), 
Kegonsa  (rr).  Lac  Court  Oreilles  (ss).  Lac  la  Belle  (r).  Little  Crooked  (rr), 
Little  Wood  (r).  Long  (1)  (rr).  Long  (3)  (rr).  Lower  Nashotah  (rr).  Lynx 
(sss),  Mary  (rr),  Mendota  (c),  Mercer  (rr).  Mill  (rr)  Mud  (2)  (c),  Nancy  (s), 
Oconomowoc  (r),  Okauchee  (rr).  Palmer  (rr).  Pine  Tree  (rr).  Poplar  (rr). 
Round  (1)  (rr).  Round  (3)  (r),  Rudolph  (rrr),  Sanford  (c).  Shell  (rrr), 
Sishebogema  (rr).  South  Crab  (rr),  Squirrel  (rr).  Upper  Nashotah  (r).  Upper 
Nemahbin  (rr),  Waubesa  (c).  Wildcat  (sss).  Wolf  (r). 

var.  Treleasii  Bornet  et  Flahault.  PI.  10,  Figs.  5-7. 

Ann.  Sci.  Nat.  7 Ser.  Bot.  7:  230.  1888. 

Anahaena  mendotae  Trelease,  Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  7:  123, 
pi.  10,  fig.  5.  1889. 

Cells  smaller  and  with  spores  somewhat  narrower  and  proportionally 
longer.  ( Euplanktont ) . 

Vegetative  cells  3-5  /x  broad,  4.5-12  /x  long;  heterocysts  4.5-6  /x  broad, 
6-8  /X  long ; spores  6-8  /x  broad,  20-40  fx  long. 

Mendota  (aa),  Waubesa  (s). 


WISCONSIN  PHYTOPLANKTON 


61 


Anabaena  Lemmermanni  P.  Richter.  PI.  10,  Fig.  8 ; PI.  11,  Fig.  1. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  10;  153.  1903. 

Anabaena  flos-aquae  Klebahn  non  (Lyngbye)  de  Breb.,  Flora  80:  267,  pi.  4, 
figs.  21-22.  1895. 

Filaments  free-floating ; irregularly  or  circinately  interwoven  to  form 
a spherical  or  broadly  ellipsoid  mass,  with  filaments  frequently  radiat- 
ing in  loops  from  a common  center.  Vegetative  cells  spherical  or 
slightly  elongate,  usually  containing  numerous  pseudovacuoles.  Heter- 
ocysts spherical,  approximately  the  same  size  as  the  vegetative  cells. 
Spores  cylindrical,  with  rounded  ends,  with  inner  side  straight  and  the 
outer  convex;  rarely  remote  from  heterocysts,  generally  forming  short 
catenate  series  on  both  sides  of  heterocysts  and  lying  in  a dense  mass 
at  the  center  of  the  colony.  The  spore  masses  and  heterocysts  fre- 
quently persisting  long  after  the  disappearance  of  the  vegetative  cells. 
(Euplanktont). 

Vegetative  cells  5.5-7  /a  broad,  5-8  long;  heterocysts  6-7.5  /x  broad; 
spores  8-11  /x  broad,  19-33  fx  long. 

Crawling  Stone  (rr),  Diamond  (r),  Kawaguesaga  (rr),  Long  (rr),  Marl 
(r),  Oconomowoc  (r),  Paddock  (cc),  Palmer  (r),  Pardee  (ss),  Rainbow  (2) 
(rr),  Reserve  (r).  Rice  (1)  (s),iSand  (2)  (rr),  Taylor  (ss),  Trout  (s). 

The  species  differs  from  A.  fios-aquae  in  the  regular  looping  of  the 
trichomes  from  a common  center  and  the  development  of  a large  mass 
of  spores  at  the  center  of  the  colony.  The  persistence  of  the  spores 
after  the  disappearance  of  the  vegetative  cells  is  very  common  and 
certain  of  the  records  for  the  species  are  based  upon  observation  of  the 
spore  masses  only. 

APHANIZOMENON  Morren  1838. 

Trichomes  straight  slightly  flexed,  or  curved ; in  lateral  contact  with 
one  another  to  form  small,  macroscopic,  free-floating,  feathery,  plate 
or  scale-like  opaque  colonies.  Trichomes  destitute  of  a gelatinous 
sheath,  sometimes  constricted  at  cross  walls  of  cells,  and  slightly  attenu- 
ated at  the  apices.  Cells  cylindrical,  with  flattened  ends.  Heterocysts 
intercalary,  cylindrical.  Spores  elongate,  cylindrical  and  with  flattened 
ends;  solitary,  adjacent  to  or  remote  from  the  heterocysts. 

Reproduction  by  the  formation  of  hormogones  and  resting  spores. 

Aphanizomenon  flos-aquae  (L)Ralfs.  PI.  11,  Pigs.  2-4. 

Ann.  & Mag.  of  Nat.  Hist.  2 Ser.  5:  340,  pi.  9,  fig.  6.  1850;  Klebahn,  Flora  80; 
271,  pi.  4,  figs.  27-30.  1895. 

Trichomes  straight  or  slightly  curved,  laterally  joined  to  form  a flat 
flake-  or  scale-like  plate.  Cells  cylindrical,  with  flattened  ends,  about 


62 


WISCONSIN  PHYTOPLANKTON 


three  times  as  long  as  they  are  broad,  generally  with  numerous  pseudo- 
vaeuoles.  Heterocysts  cylindrical,  with  straight  or  slightly  convex  sides, 
without  a distinct  polar  nodule.  Spores  elongate,  cylindrical,  with 
rounded  or  somewhat  flattened  ends,  generally  some  distance  from  the 
heterocysts.  ( Euplanktont ) . 

Cells  4-6  IX  broad,  5-15  fx  long;  heterocysts  5-7  ^x  broad,  7-20  jx  long; 
spores  6-8  fx  broad,  35-80  fx  long. 

Amicoy  (aa),  Balsam  (ss),  Bear  (3)  <rr),  Beaverdam  (rr),  Big  (r),  Big 
Butternut  (rr),  Birch  (1)  (c),  Bone  (rr),  Camp  (r),  Catfish  (sss),  Center 
(rrr),  Chetac  (aaa),  Cranberry  (ss).  Crawling  Stone  (rrr),  Deer  (rrr),  Dun- 
ham (rr).  Found  (rr),  Fowler  (rr).  Granite  (a),  Green  (2)  (ss).  Half  Moon 
(sss),  Hillman  (sss).  Hooker  (cc).  Horse  (rrr).  Horseshoe  (1)  (rr).  Island 
(c),  Kawaguesaga  (ccc),  Kegonsa  (cc).  Lac  la  Belle  (rr).  Little  Bass  (2)  (rr), 
Little  Butternut  (s).  Little  Rice  (1)  (s).  Little  V/ood  (rr).  Long  (3)  (rr). 
Lost  (ss).  Loveless  (ss).  Lower  Nashotah  (rr),  Mendota  (s),  Mud  (3)  (rr), 
Nagawicka  (rr).  North  Twin  (rrr),  Oconomowoc  (rr),  Okauchee  (rr),  Pardee 
(cc),  Pewaukee  (rr).  Pike  (rr).  Plum  (r),  Pokegama  (2)  (rrr),  Pokegama 

(3)  (aaa).  Poplar  (rrr).  Prairie  (aaa).  Reserve  (rr).  Rice  (1)  (ss),  Round 
(1)  (sss).  Round  (2)  (ss),  St.  Croix  (ccc).  Sand  (1)  (r).  Sand  (3)  (r).  Sand 

(4)  (r),  Sanford  (sss),  Shell  (rrr).  South  Turtle  (sss).  Squirrel  (a),  Streitor 
(rr),  Tied  Canoe  (sss).  Upper  Nashotah  (rr).  Upper  Nemahbin  (r).  Upper 
Turtle  (rr),  Vermilion  (r),  Waubesa  (s),  White  Ash  (rr),  Whitefish  (rr). 
White  Sand  (ss),  Winnebago  (r). 

When  the  alga  occurs  in  any  quantity  the  lake  appears  to  be  fllled 
with  small  pieces  of  macerated  grass  and  it  is  one  of  the  few  plankton 
genera  that  can  be  determined  without  the  aid  of  a microscope.  The 
colony  is  so  opague  that  the  heterocysts  cannot  be  seen  while  the  colony 
is  intact  but  after  a mount  has  been  standing  a few  minutes  the  colonies 
begin  to  dissociate  into  the  component  filaments  and  observation  of  the 
heterocysts  and  spores  is  then  an  easy  matter.  The  colonies  are  fre- 
quently sterile  and  it  is  generally  only  during  the  colder  months  of  the 
year  that  there  is  a formation  of  spores. 


Family  ElVULARIACEAE. 

Filaments  rarely  solitary,  generally  forming  sessile  or  free-floating 
spherical,  hemispherical,  or  amorphous  colonies.  Trichomes  gradually 
attenuated  from  a broad  basal  cell  to  a hair-like  apical  cell.  Sheaths 
copious,  homogeneous  or  lamellated,  hyaline  or  colored,  firm  or  gelat- 
inous; enclosing  one  or  more  trichomes.  Cells  hemispherical,  spheri- 
cal, or  disciform  with  convex  sides  at  the  basal  portion  of  the  triehome, 
elongate  cylindrical  in  the  apical  region.  Cell  contents  variously  col- 
ored ; homogeneous,  granulose,  or  with  numerous  pseudovacuoles.  Trich- 
omes simple  or  with  “false  branching’’.  Heterocysts  solitary;  usually 


WISCONSIN  PHYTOPLANKTON 


63 


at  base  of  triehomes,  rarely  intercalary.  Spores,  when  present,  soli- 
tary and  adjacent  to  heterocysts. 

E-eprodnction  by  formation  of  triehomes  and  spores. 

GLOEOTRICHIA  J.  G.  Agardh  1842. 

Filaments  always  in  colonies;  free-floating  or  sessile;  spherical  to 
hemispherical,  tough  and  leathery  to  gelatinous,  hyaline  or  colored. 
Triehomes  attenuated  to  fine  hair-like  processes  at  the  distal  end,  en- 
closed by  gelatinous  sheaths  that  are  distinct  at  the  base  and  confluent 
at  the  apex.  Filaments  containing  one  triehome,  but  at  times  showing 
false  branching.  Heterocysts  spherical  to  hemispherical,  solitary;  at 
the  base  of  the  triehomes.  Spores  cylindrical,  solitary,  always  adjacent 
to  the  heterocysts.  Vegetative  cells  convexly  disciform  to  short  cylin- 
drical at  base  of  triehomes,  elongate  cylindrical  with  straight  sides  at 
apex  of  triehomes. 

Reproduction  by  hormogones  and  resting  spores. 

Gloeotrichia  echinulata  ( J.  E.  Smith)  P.  Richter.  PI.  11,  Pigs.  5-6. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  2:  31,  figs.  1-8.  1894. 

Conferva  echinulata  J.  E.  Smith,  Eng.  Bot.,  pi.  1378.  1804. 

Rivularia  echinulata  J.  E.  Smith,  Eng.  Bot.  index;  P.  Richter,  Forschungsbr. 
a.  d.  Biol.  Stat.  zu  Plbn  2:  45.  1894;  Lemmermann,  Kryptogamenfi.  d.  Mark 

Brandenburg  3,  Algen  1:  255,  245,  figs.  1,  6.  1907. 

Gloeotrichia  pisum  Bornet  et  Flahault  (p.p.)  non  Thuret,  Bull.  Soc.  Bot. 
France  31:  80.  1884;  Ann.  Sci.  Nat.  7 Ser.  Bot.  4:  366.  1886;  Trelease,  Trans. 

Wis.  Acad.  Sci.,  Arts,  & Lett.  7:  124-125  (with  fig.)  1889. 

Colonies  always  free-floating,  spherical;  up  to  2 mm.  in  diameter. 
Filaments  radially  arranged  about  a common  center  but  becoming  ir- 
regular in  arrangement  on  slight  pressure.  Sheaths  hyaline,  homogene- 
ous, distinct  at  base,  apex  frequently  confluent  with  colonial  envelope. 
Triehomes  broad  at  base,  attenuated  to  long,  colorless,  hair-like  pro- 
cesses. Lowest  vegetative  cell  of  triehome  hemispherical ; those  a short 
distance  from  base  disciform  with  markedly  convex  sides;  those  in 
middle  of  triehome  cylindrical ; while  the  cells  in  the  apical  region  are 
elongate  cylindrical.  Basal  cells  completely  filled  with  cytoplasm, 
apical  cells  with  cytoplasm  restricted  to  the  median  portion.  Cell  con- 
tents rarely  homogeneous,  usually  with  numerous  pseudovacuoles. 
Heterocysts  at  base  of  triehome,  spherical.  Spores,  when  present,  ad- 
jacent to  heterocysts,  elongate  cylindrical  with  rounded  ends. 

Cells  at  base  of  triehome  8-10  /x  broad;  at  apex  1-2  fx  broad;  hetero- 
cysts 7-10  fx  broad ; spores  8-10  fx  broad,  40-54  fx  long. 

Bass  (3)  (rr).  Bear  (3)  (rr).  Bear  Trap  (rr),  Beaverdam  (rr),  Birch  (2) 
(ss),  Birch  Island  (r),  Bone  (rr),  Carroll  (rr),  Catherine  (sss),  Chetac  (ss), 


64 


WISCONSIN  PHYTOPLANKTON 


Clare  (ss),  Crawling  Stone  (rrr),  Des  Moines  (cc),  Diamond  (ss),  Duck  (rr). 
Dummy  (rr),  Dutchmans  (ss),  Fish  (ss),  Fowler  (sss).  Grindstone  (rr). 
Half  Moon  (ss).  Horseshoe  (1)  (ss).  Horseshoe  (2)  (rr),  Howey  (rr),  Island 
(ss),  Jennie  (rr),  Kegonsa  (aa),  Kimball  (rr),  Lac  Court  Oreilles  (ss).  Lake 
of  the  Woods  (r),  Lindy  (rr),  Long  (1)  (sss).  Loon  (r),  Mendota  (s),  Monona 
(cc),  Nancy  (ss).  North  Twin  (r),  Mercer  (rrr).  Middle  McKenzie  (ss),  Mud 
(3)  (aa),  Oconomowoc  (rr),  Owen  (rrr),  Razorback  (aa).  Reserve  (rr),  St. 
Croix  (rr).  Sand  (1)  (rr).  Sand  (3)  (rr).  Shell  (rr).  Soft  (rr).  Trout  (cc), 
Waubesa  (cc),  Whitefish  (sss).  Wild  Goose  (rr),  Winnebago  (r). 

A bloom  of  this  alga  can  be  recognized  at  once  by  the  minute  seed-like 
colonies  surrounded  by  an  aureole  of  whitish  threads.  It  was  first 
noted  by  Davis  in  England  in  1804  and  the  plant  figured  and  described 
by  Smith  in  his  English  Botany.  The  various  references  to  the  alga 
before  the  recognition  of  a definite  plankton  flora  have  been  compiled 
by  Bornet  and  Flahault  as  well  as  P.  Richter.  Since  the  study  of  the 
plankton  flora  by  phycologists  the  alga  has  been  found  in  the  lakes  of 
iQOst  European  countries.  Although  there  seems  to  be  but  a single 
species  of  the  Rivulariaceae  found  free-floating  in  lakes  and  ponds  the 
nomenclatorial  treatment  of  this  species  is  quite  varied.  Bornet  and 
Flahault  affirm  that  it  is  the  common  Gloeotrichia  pisum,  which  ordi- 
narily grows  attached  to  submerged  plants  along  the  shore,  that  has 
broken  away  and  become  free-floating.  They  hold  that  Rivularia 
echinulata  J.  E.  Smith  (whose  dimensions  are  the  same  as  those  of 
G.  pisum)  is  nothing  but  a free-floating  G.  pisum.  In  my  observations 
on  the  algae  of  our  lakes  there  is  no  correlation  between  the  appearance 
of  G.  pisum  and  G.  echinulata  in  the  same  lake  in  Wisconsin.  In  the 
region  of  Madison,  G.  pisum  does  not  appear  until  the  middle  of  July 
and  yet  at  one  time  there  was  a heavy  bloom  of  G.  echinulata  on  the 
28th  of  June,  a time  when  there  was  no  G.  pisum  along  the  shore.  I 
am  convinced  that  the  sessile  Gloeotrichia  is  not  the  one  found  in  the 
plankton  and  that  Richter  is  quite  right  in  reviving  the  old  specific 
name  echinulata.  Some  investigators  hold  that  Gloeotrichia  is  but  a 
sub-genus  of  Rivuluria,  but  I have  followed  Bornet  and  Flahault  in 
considering  the  two  distinct.  This  distinction  is  based  upon  the  occur- 
rence of  spores  in  Gloeotrichia  and  a lack  of  spores  in  Rivularia. 


WISCONSIN  PHYTOPLANKTON 


65 


Class  PHAEOPHYCEAE. 


Plants  usually  of  macroscopic  size  and  definitely  shaped.  Cells  vari- 
ously shaped  and  containing  brown  chromatophores  in  which  a brown 
pigment,  phaeophycin,  masks  the  chlorophyll.  Cell  wall  not  conspicu- 
ously impregnated  with  silica  and  cells  generally  immobile  in  the  vege- 
tative phases. 

Asexual  reproduction  by  vegetative  cell  division,  aplanospores,  and 
zoospores. 

Sexual  reproduction  by  isogamous  zoogametes ; or  heterogamous  with 
a fusion  of  zoogametes  of  unequal  size,  or  a union  of  a large  immobile 
oosphere  and  a small  motile  antherozooid. 

All  of  the  complex  non-motile  members  of  this  class  are  marine  and 
only  unicellular  or  simple  colonial  forms  are  found  in  fresh  waters. 
These  freshwater  forms  have  the  motile  phase  dominant,  as  a rule,  and 
form  the  subclass  Chrysomonadineae  of  the  Phaeophyceae.  Many 
place  all  of  the  colorless  or  brown  chromatophored  motile  unicellular 
organisms  in  a class  by  themselves,  the  Flagellatae,  but,  as  I have  stated 
elsewhere,  the  group  of  the  Chrysomonadineae  seems  sufficiently  related 
to  the  Phaeophyceae  to  warrant  uniting  the  two. 

Sub-class  CHRYSOMONADINEAE. 

Cells  with  one  or  more  definite,  disciform,  laminate,  or  reticulate, 
golden-brown  chromatophores.  Cells  free-swimming  or  sessile,  solitary 
or  in  colonies  of  definite  to  indefinite  shape.  Life  cycle  generally  with 
the  motile  phase  dominant  but  sometimes  developing  into  amorphous  or 
rhizopodial  palmella  stages.  Cells  either  naked  or  with  a gelatinous 
to  definitely  constituted  periplast.  Individual  cells  with  1-2  anterior 
or  lateral  cilia  of  equal  or  unequal  length;  1-10  contractile  vacuoles, 
generally  at  the  anterior  end;  with  or  without  an  eyespot;  and  with 
one  or  more  chromatophores.  Symmetry  of  cells  bilateral,  not  inter- 
rupted by  a lateral  or  longitudinal  grooving.  Nutrition  holophytic  or 
saprophytic ; assimilation  product  leucosin  or  fat,  never  starch. 

Asexual  reproduction  by  longitudinal  or  transverse  division  of  cells. 
Resting  stages  with  heavy  walls  known  in  many  genera. 

Sexual  reproduction  as  yet  unknown  in  the  sub-class. 


66 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  DIVISIONS. 

Motile  phase  dominant,  rhizopodial  or  palmella  phase  rare.EucHUYsoMONADiNAE 
Immobile  phase  dominant,  motile  phase  known  or  unknown. 

Cells  spherical  to  ovoid,  embedded  in  a gelatinous  envelope . . . Hydrurinae 
Cells  with  pseudopodial  processes Rhizochrysidinae 

Division  EUCHRYSOMONADINAE. 

Cell  structure  and  organization  as  noted  in  the  description  of  the 
sub-class.  Ciliate  phase  dominating  the  life  history.  Palmella  or 
rhizopodial  phases  known  but  not  the  general  rule. 


KEY  TO  THE  ORDERS. 


Motile  phase  with  one  flagellum Chromulinales 

Motile  phase  with  two  flagella. 

Flagella  of  the  same  length Isochrysidaues 

Flagella  of  unequal  length Ochromonadales 


Order  CHROMULINALES. 

Cells  generally  solitary,  rarely  colonial ; free-floating  or  sessile.  ‘ Mo- 
tile phase  with  a single  apical  flagellum.  Chromatophores  reticulate, 
laminate,  or  disciform ; generally  two  in  each  cell.  Apical  contractile 
vacuoles  present  or  lacking.  Cells  either  naked  or  with  a deflnite,  homo- 
geneous or  sculptured  periplast. 

Reproduction  by  vegetative  division  of  cells.  Thick-walled  resting 
stages  known  in  certain  genera. 


KEY  TO  THE  FAMILIES. 


Cells  naked  Euohromtjlinaceae 

Cells  with  a differentiated  periplast Mallomonadaceae 


Family  EUCHROMULINACEAE. 

Cells  naked,  without  a differentiation  of  the  periplast.  Cells  with 
sharply  defined  disciform  to  laminate  chromatophores,  and  without 
contractile  vacuoles.  Flagellum  single. 

There  are  several  genera  with  many  species  in  the  family  but  only 
one  of  them,  Chrysamoeha,  has  been  noted  in  the  plankton  of  the  state. 


WISCONSIN  PHYTOPLANKTON 


67 


CHRYSAMOEBA  Klebs  1893. 

Cells  solitary,  free-floating,  with  a mono-flagellate  motile  phase  and 
an  amoeboid  non-motile  phase.  Motile  phase  broadly  ovoid,  naked, 
with  two  elongate,  laminate,  golden-brown  chromatophores ; a large 
non-contractile  vacuole,  2-3  small  contraetile  vacuoles;  and  a single 
flagellum  slightly  longer  than  the  cell.  Eye-spot  lacking. 

Non-motile  phase  solitary  or  in  small  clumps,  with  several  simple  or 
branching  pseudopodial  processes  extending  in  all  directions.  Chro- 
matophores and  vacuoles  as  in  the  motile  phase. 

Chrysamoeba  radians  Klebs.  PI.  12,  Fig.  1. 

Zeits.  f.  wiss.  Zool.  55:  406,  pi.  18,  iigs.  la-lb,  1893. 

Speciflc  characters  as  described  above.  (Euplanktont). 

Motile  phase  8-10  /x,  broad,  12-15  long;  amoeboid  phase  (without 
processes)  12-17  fx  broad,  (with  processes)  35-40  p.  broad. 

Round  (4)  (rr),  Taylor  (rr). 

Family  MALLOMONADACEAE. 

Cells  always  free-swimming,  solitary  or  colonial,  never  metamorphos- 
ing into  a palmella  or  rhizopodial  phase.  Periplast  of  cells  or  colonial 
envelope  with  numerous  small  plates  of  silica  that  have  long,  siliceous, 
needle-like  processes.  Cells  ovoid  to  ellipsoid,  with  one  flagellum,  a 
number  of  contractile  vacuoles  and  two  long  laminate  chromatophores. 

KEY  TO  THE  GENERA. 

Cells  solitary Maixomonas 

Cells  in  spherical  colonies  Chbysosphaebklla 

MALLOMONAS  Perty  1852. 

Cells  always  solitary,  free-swimming,  with  a single  flagellum  at  the 
anterior  end.  Periplast  of  cells  with  small  circular  or  angular  siliceous 
discs  covering  the  entire  surface  of  the  cell  or  restricted  to  one  or  both 
ends.  Scales  frequently  arranged  in  regular  transverse  or  diagonal 
rows,  produced  into  a single,  long,  simple  or  toothed,  needle-like  setae. 
Cells  containing  one  or  more  contractile  vacuoles  that  may  be  apical, 
median,  or  basal  in  position.  Chromatophores  two,  parietal,  laminate, 
and  golden-brown  in  color.  Assimilation  product  leucosin. 

Reproduction  by  vegetative  cell  division  parallel  to  the  long  axis. 
Akinetes  known  in  many  species. 


68 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 

Setae  restricted  to  one  end  of  the  cell. 

Apical  end  with  setae. 


Cells  cylindrical M.  Alpina 

Cells  ovoid M.  Tonsurata 

Basal  end  with  setae M.  Producta 

Setae  covering  whole  cell M.  Caudata 


Mallomonas  alpina  Pascher  & Kuttner.  PI.  12,  Fig.  4. 

in  Pascher,  D.  Siisswasserfl.  Deutschl.,  osterr.,  u.  d.  Schw.  2,  Flagellatae  2:  36, 
fig.  58a.  1913. 

Cells  ellipsoid  to  elongate  cylindrical,  with  poles  rounded  or  pointed. 
Scales  rhomboidal,  in  diagonal  rows;  with  a single,  long,  straight  or 
curved  seta.  Setae  confined  to  anterior  end  of  cells.  (Euplanktont). 
Cells  8-12  broad,  25-45  long. 

Camp  (r).  ‘ 

Mallomonas  producta  (Zacharias)  Iwanofi.  PI.  12,  Fig.  2. 

Bull,  de  TAcad.  Imp.  d.  Sc.  de  St.  Petersbourg  5 Ser.,  11:  250,  pi.  A,  figs.  4-6. 
1899. 

Cells  cylindrical,  with  straight  or  slightly  convex  sides,  ends  rounded 
and  tapering.  Scales  in  regular  transverse  to  diagonal  rows,  diamond- 
shaped  or  laterally  elongate.  Setae  straight  or  bent,  confined  to  basal 
portion  of  cell.  Chromatophores  two,  golden-brown,  laminate,  and 
parietal.  (Euplanktont). 

Cells  9-13  fi  broad,  40-70  /x  long. 

Catfish  (sss).  Cranberry  (ss),  Crawling  Stone  (sss),  Lac  la  Belle  (ss). 
Long  (1)  (ss),  Otter  (r).  South  Turtle  (rrr),  Upper  Nashotah  (rr). 

var.  MARCHiCA  Lemmermann.  PI.  12,  Pig.  3. 

Zeits.  f.  Fischeri  1903:  106.  1903. 

Cells  shorter  and  relatively  broader.  Setae  sometimes  at  both  ends 
of  cells.  (Euplanktont). 

Cells  11-12  fx  broad,  21-26  jx  long. 

Nancy  (r),  Oconomowoc  (ss),  Tamarack  (ss). 

Mallomonas  tonsurata  Teiling.  PI.  12,  Fig.  5. 

Sv.  Bot.  Tids.  6:  277,  fig.  3.  1912. 

Cells  ellipsoid,  with  posterior  end  rounded  and  anterior  end  pointed. 
Setae  confined  to  anterior  third  of  cell,  fairly  short  and  somewhat 
curved.  Scales  not  regularly  arranged.  (Euplanktont). 

Cells  7-8  IX  broad,  about  18  /a  long. 

Waupaca  (rr). 


WISCONSIN  PHYTOPLANKTON 


69 


Mallomonas  caudata  Iwanoff.  PI.  12,  Fig.  6. 

Bull,  de  I’Acad.  Imp.  d.  Sc.  de  St.  Pdtersbourg  5 Ser.,  11:  250,  PI.  B,  iigs.  1-8. 
1899. 

Cells  broadly  ovoid,  with  posterior  end  narrower  than  the  anterior. 
Scales  oval,  arranged  in  transverse  series.  Setae  long,  covering  the 
entire  surface  of  the  cell  and  frequently  with  minute  teeth-like  projec- 
tions at  the  distal  end.  Cells  with  two  long,  parietal,  laminate,  chro- 
inatophores.  (Euplanktont). 

Cells  12-30  fi  broad,  40-85  long. 

Beasley  (rr),  Birch  (1)  (rrr),  Browns  (rr),  Carson  (rrr),  Catherine  (rr), 
Clare  (r),  Clear  Crooked  (rr),  Crab  (rr).  Crawling  Stone  (rrr).  Diamond 
(rrr).  Hill  (ss),  Jennie  (rr).  Kitten  (sss).  Lac  la  Belle  (ss).  Long  (3)  (ss), 
Long  (4)  (rr).  Lynx  (rr).  Mud  (2)  (ss).  No  Mans  (s),  North  Turtle  (r), 
Okauchee  (rr).  Otter  (sss),  Pokegama  (1)  (rr),  Pokegama  (2)  (r).  Red  Basa 
(s),  Rock  (cc),  Round  (1)  (sss),  Rudolph  (sss),  St.  Croix  (rrr).  Sand  (4) 
(sss),  Sanford  (sss).  South  Crab  (rr).  Wildcat  (sss).  Wild  Goose  (rr).  Wolf 
(rr). 


CHRYSOSPHAERELLA  Laut^rborn  1896. 

Cells  ellipsoid  to  pyriform,  in  spherical  colonies  of  microscopic  size 
tliat  are  partially  embedded  in  a spherical,  hyaline,  gelatinous  envelope 
containing  numerous,  tangentially  placed,  minute  plates  of  silica.  An- 
terior ends  of  cells  with  two  short,  vase-shaped  projections,  each  bear- 
ing a single,  long,  straight,  siliceous  seta  of  some  length.  Cells  with 
one  anterior  flagellum ; two  elongate,  parietal,  golden-brown  chromato- 
phores ; and  several  vacuoles. 

Reproduction  by  vegetative  cell  division.  Resting  akinetes  unknown. 

Chrysosphaerella  longispina  Lauterborn.  PI.  12,  Figs.  7-8. 

Zool.  Anz.  19:  16.  1896;  Zeits.  f.  wiss.  Zool.  65:  381,  pi.  18,  figs.  12-16.  1899. 

Speciflc  characters  as  described  above.  (Euplanktont). 

Average  breadth  of  cells  9 /a,  average  length  15  fi.  Colonies  50-250  /u 
in.  diam. 

Bettine  (rr),  Blue  Gill  (ss),  Boulder  (rrr).  Canteen  (r),  Elizabeth  (rr). 
Hill  (aa).  Lac  la  Belle  (rr).  Long  (4)  (rr),  Lynx  (r).  Marl  (rr),  Mary  (ss). 
No  Mans  (rr),  Oconomowoc  (ss),  Okauchee  (s).  Otter  (ss).  Rainbow  (ss). 
Round  (4)  (rr),  Rudolph  (sss),  Silver  (2)  (ss).  South  Turtle  (cc),  Upper 
Nemahbin  (ss).  Wild  Goose  (ccc). 

Order  ISO CHRYSID ALES. 

Cells  free-floating  or  sessile,  solitary  or  colonial,  naked  or  with  a 
definite  homogeneous  or  sculptured  periplast.  Motile  phase  always 
present,  palmella  or  rhizopodial  phase  lacking.  Cells  variously  shaped, 


70 


WISCONSIN  PHYTOPLANKTON 


always  with  two  apical  cilia  of  equal  length ; generally  with  two  lami- 
nate, parietal,  golden-brown  chromatophores  and  without  an  eyespot. 

The  only  family  represented  in  the  flora  of  the  state  is  that  of  the 
Euhymenomonadaceae. 

Family  EV HYMEN  OMON  AD  ACE  AE. 

Differing  from  other  families  of  the  order  in  having  a definite  sculp- 
tured periplast  and  an  anterior  vacuolar  system.  Synura  the  sole 
representative. 


SYNURA  Ehrenberg  1838. 

Cells  radially  arranged  in  spherical  to  oblong-ovoid  free-swimming 
colonies  that  are  not  enclosed  by  a gelatinous  sheath.  Individual  cells 
broadly  pyriform,  with  the  narrower  end  towards  the  center  of  the 
colony.  Outer  portion  of  cells  firm,  with  small  spines,  reticulations, 
or  combinations  of  the  two.  Cells  with  two  long  anterior  cilia  of  equal 
length,  several  vacuoles,  two  long  laminate  parietal  chromatophores, 
and  without  an  eyespot. 

Reproduction  by  division  of  cells  and  liberation  of  cell  contents  to 
form  amoeboid  cells.  Akinete  formation  also  known. 

Synura  uvella  Ehrenberg.  PI.  12,  Figs.  9-10. 
Infusionsthierchen  61,  pi.  3,  figs.  9^-9®.  1838. 

Exterior  of  cells  covered  with  fine  spines  that  are  generally  limited 
to  the  anterior  portion.  (Facultative  Planktont). 

Cells  8-17  broad,  20-35  fi  broad.  Colonies  up  to  350  /a  in  diam. 

Camp  (ss),  Canteen  (cc).  Crawling  Stone  (rrr),  Fowler  (cc),  Jenny  (rr), 
Kawaguesaga  (rr),  Little  Bear  (rrr).  Little  Crooked  (rr).  Long  (3)  (r), 
Lower  Nemahbin  (rr).  Lynx  (r),  Mendota  (ss),  Mercer  (rr).  Mill  (ccc),  Mud 
(2)  (rr),  Nagawicka  (cc),  Nancy  (cc),  Nicaboyne  (rr).  No  Mans  (cc),  North 
Turtle  (rr),  Oconomowoc  (s).  Palmer  (c),  Pardee  (sss),  Pewaukee  (sss), 
Pope  (rrr).  Rainbow  (1)  (rr).  Red  Bass  (ss).  Round  (1)  (sss),  Rudolph  (sss). 
Sand  (4)  (rr),  Sanford  (ss),  South  Turtle  (rr). 


Order  OCHROMONADALES. 

Cells  solitary  or  colonial,  free-swimming  or  sessile,  not  forming  pal- 
mella  or  rhizopodial  stages.  Cells  naked,  or  with  a definitely  shaped  re- 
ceptacle ; two  lateral  or  apical  cilia  of  unequal  length,  one  or  two  golden- 
brown  disciform  to  laminate  chromatophores ; contractile  vacuoles ; and 
an  eyespot. 


WISCONSIN  PHYTOPLANKTON 


71 


KEY  TO  THE  FAMILIES. 

Cells  naked,  at  times  in  a gelatinous  envelope  but  never  a 


definite  receptacle  Ochbomonadageae 

Cells  within  a definite  receptacle Dinobryaceab 


Family  OCHROMONADACEAE. 

Cells  solitary  or  in  colonies,  always  free-swimming,  not  enclosed  by 
a definite  receptacle  but  at  times  with  a hyaline,  homogeneous,  gelat- 
inous envelope.  Cells  with  two  apical  cilia  of  unequal  length,  one  or 
two  golden-brown  chromatophores,  an  eyespot  and  contractile  vacuoles. 

Uroglenopsis  is  the  only  representative  in  the  local  flora. 

UROGLENOPSIS  Lemmermann  1899. 

Colonies  free-swimming,  with  the  cells  embedded  in  a single  layer  at 
the  periphery  of  a copious,  hyaline,  homogeneous,  gelatinous  matrix  of 
spherical  to  broadly  ellipsoid  shape.  Arrangement  of  cells  radial  or 
somewhat  irregular.  Cells  spherical  to  narrowly  ellipsoid;  with  two 
cilia  of  unequal  length;  two  vacuoles  at  the  anterior  end;  one  or  two 
laminate  to  disciform,  parietal,  golden-brown  chromatophores ; and  with 
or  without  an  eyespot. 

Reproduction  by  vegetative  cell  division. 

Uroglenopsis  Americana  (Calkins)  Lemmermann.  PI.  13,  Figs.  1-4. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plbn  7:  107.  1899;  Kryptogamenfl.  d.  Mark 
Brandenburg  3,  Algen  1 : 449,  444,  figs.  1-3,  4-6.  1908. 

Vroglena  americana  Calkins,  Ann.  Kept.  Mass.  State.  Bd.  of  Health  23  : 655, 
Vl.  4,  figs.  1-4.  1892;  Moore,  Bot.  Gaz.  23;  105,  pi.  10,  figs.  1-11.  1897. 

Colonies  free-swimming,  generally  spherical.  Cells  ellipsoid,  with 
one  basal  or  lateral,  parietal,  disciform  to  laminate  chromatophore.  Eye- 
spot  single.  Cilia  of  unequal  length,  with  the  longer  2-3  times  the 
length  of  the  cell,  the  shorter  %-i/2  the  length  of  the  ceU.  (Euplank- 
tont). 

Cells  3-7  [1.  broad,  5-10  long.  Colonies  up  to  500  fi  in  diam. 

Beasley  (cc),  Bettine  (ss).  Browns  (ss),  Camp  (ss),  Carson  (rrr).  Diamond 
(rr).  Eagle  (sss),  Fowler  (cc),  Howey  (rr),  Lac  la  Belle  (ss).  Long  (3)  (ss). 
Long  (4)  (rr).  Lower  Nemahbin  (rr),  Lynx  (rr),  Mendota  (ss).  Mill  (ss). 
Mud  (4)  (cc),  Nancy  (rr),  Oconomowoc  (ss),  Okauchee  (rrr),  Otter  (ss), 
Paddock  (s),  Pewaukee  (rr).  Rainbow  (1)  (ss).  Round  (4)  (rr),  Taylor  (ss). 
Wildcat  (ss),  Wolf  (rr),  Youngs  (cc). 


72 


WISCONSIN  PHYTOPLANKTON 


Family  DINOBRYONACEAE. 

Cells  solitary  or  in  colonies,  free-floating  or  sessile.  Always  attached 
to  the  base  of  a conical  to  vase-like,  colored  or  hyaline,  smooth  or  sculp- 
tured receptacle.  Cells  with  one  or  two  laminate  chromatophores,  con- 
tractile vacuoles,  an  eyespot,  and  two  cilia  of  unequal  length. 

KEY  TO  THE  GENERA. 


Receptacles  homogeneous,  without  growth  rings Dinobryon 

Receptacles  with  successive  growth  rings Hyalobryon 


DINOBRYON  Ehrenberg  1835. 

Cells  free-floating,  sessile,  or  epiphytic;  solitary  or  in  colonies;  at- 
tached to  the  bottom  of  conical,  campanulate,  or  cylindrical  receptacles 
with  open  apices  and  pointed  bases.  Colonial  species  arbuscular,  each 
receptacle  with  the  pointed  ends  of  1-4  other  receptacles  in  its  mouth. 
Development  of  branching  indefinite.  Protoplast  spindle-shaped,  coni- 
cal, or  ovoid ; attached  by  a stalk  to  the  base  of  the  receptacle.  Anterior 
end  of  protoplast  with  two  cilia  of  unequal  length  that  project  beyond 
the  open  end  of  the  receptacle.  Cells  with  one  or  two  laminate,  elon- 
gate, parietal,  golden-brown  chromatophores;  several  apical,  lateral,  or 
basal  contractile  vacuoles;  and  one  apical  eyespot.  Assimilation  pro- 
duct generally  leucosin. 

Reproduction  by  longitudinal  division  of  cell  contents  to  form  ovoid 
daughter  cells  that  migrate  to  the  mouth  of  the  old  receptacle  or  leave 
it  entirely  before  developing  new  receptacles.  Akinetes  known. 

The  specific  limits  of  colonial  plankton  species  of  this  genus  are  very 
poorly  defined  and  it  is  almost  impossible  to  draw  a sharp  line  of  de- 
marcation between  the  various  species.  I have  indicated  as  species  the 
centers  around  which  the  variations  seem  to  occur. 

KEY  TO  THE  SPECIES. 


Cells  solitary. 

Cell  shape  conical,  elongate D.  CAijoiFOBMa 

Cells  broadly  spindle-shaped D.  Tabellabiae 

Cells  in  colonies. 

Branching  of  cells  markedly  divergent D.  Diveegens 

Branching  of  cells  not  sharply  divergent. 

Cells  elongate  conical. 

Sides  of  receptacles  straight D.  Stipitatum 

Sides  of  receptacles  undulate D.  Bavaricum 

Cells  campanulate D.  SEn'ULARiA 


WISCONSIN  PHYTOPLANKTON 


73 


Dinobryon  caliciforme  Bachmann.  PL  13,  Figs.  5-6. 

Arch.  f.  Hydrob.  u.  Planktonkde.  3:  82,  fig.  1908. 

Cells  solitary;  epiphytic  upon  the  gelatinous  envelope  of  various 
colonial  Myxophyceae.  Receptacles  elongate  conical,  with  a sharply 
pointed  base.  Protoplast  the  same  shape  as  the  lower  two-thirds  of  re- 
ceptacle. Chromatophores  two,  laminate,  parietal,  and  golden-brown 
in  color,  Eyespot  single.  Cilia  not  as  long  as  the  cell.  (Euplank- 
tont) . 

Receptacles  5-6  fx  broad  at  apex,  30^0  fx  long. 

Embedded  in  or  on  gelatinous  envelope  of  Coelosphaerium  Naegeli- 
anum  and  Microcystis  aeruginosa. 

Browns  (sss). 

Dinobryon  tabellariae  (Lemmermann)  Pascher.  PL  13,  Figs.  7-9. 

Siisswasserfl.  Deutschl.,  osterr.  u.  d.  Schw.  2,  Flagellatae  2:  66,  figs.  105»-105b. 
1913. 

Dinobryon  utriculus  var.  tabellariae  Lemmermann,  Arkiv  for  Botanik  2, 
No.  2:  119,  pi.  1,  fig.  19.  1904. 

Cells  solitary;  epiphytic  upon  filaments  of  Tahellana.  Receptacle 
broadly  spindle-shaped,  with  the  base  produced  into  a short  stipe.  Pro- 
toplast attached  to  side  of  lower  portion  of  receptacle,  ovoid  in  shape 
and  with  the  usual  contents  of  the  genus.  (Euplanktont). 

Receptacles  7-10  fx  broad  at  center,  4-5  at  apex ; 18-22  fx  long. 

Crawling  .Stone  (r).  Long  (3)  (rr).  Sand  (4)  (s). 

Dinobryon  bavaricum  Imhof.  PL  13,  Fig.  10. 

Zool.  Anz.  13:  484.  1890;  Lemmermann,  Bot.  Not.  1903  : 78,  pi.  3,  figs.  3-4. 
1903. 

Cells  in  free-floating  compact  colonies.  Receptacles  of  individual 
cells  elongate-conical.  Base  of  receptacle  very  much  produced  with 
sides  almost  parallel;  expanded  portion  of  receptacle  with  undulate 
sides.  Seasonal  variation  pronounced,  the  receptacles  being  much 
longer  during  the  summer.  (Euplanktont). 

Receptacles  6.5-8. 5 fx  broad ; 45-100  long. 

George  (ss),  Harris  (rr),  Marl  (ss),  Oconomowoc  (ss),  Speese  (ss),  Tied 
Canoe  (ss).  White  Sand  (s). 


74 


WISCONSIN  PHYTOPLANKTON 


Dinobryon  stipitatum  Stein.  PI.  13,  Fig.  11. 

Der  Organismus  der  Infusionstiere  3:  pi.  12,  iig.  5.  1878;  Pascher,  D.  Suss- 

wagserfl.  Deutschl.  osterr.  u.  d.  Schw.  2,  Flagellatae  2:  73,  -fig.  118.  1913. 

Cells  always  in  narrow,  fairly  dense,  free-floating  colonies.  Recep- 
tacles of  individual  cells  elongate-conical,  with  bases  produced  into  stipes 
with  nearly  parallel  sides.  Sides  of  receptacle  not  undulate.  Indi- 
vidual receptacles  of  colony  not  divergent  from  one  another.  Seasonal 
variation  chiefly  in  elongation  of  apical  cells  of  colony.  (Facultative 
Planktont) . 

Receptacles  6-8  /a  broad ; 56-96  fi  long. 

Marl  (ss),  Oconomowoc  (cc).  Round  (4)  (sss),  iSouth  Turtle  (rr). 

Dinobryon  sociale  Ehrenberg.  PI.  13,  Fig.  12. 

Abh.  d.  k.  Ak.  d.  Wiss.  Berlin  1833;  279.  1835;  Die  Infusionsthiercben  125, 
pi.  8,  fig.  9.  1839;  Pascher,  Siisswasserfl.  Deutschl.  osterr.  u.  d.  Schw.  2, 

Flagellatae  2:  73,  figs.  116-117.  1913. 

Cells  in  free-floating  colonies.  Individual  receptacles  somewhat  di- 
vergent from  one  another  and  producing  a fairly  loose  colony.  Recep- 
tacles conical,  sometimes  slightly  constricted  below  the  open  mouth,  with 
bases  gradually  tapering  to  a sharp  point  that  is  not  extended  to  form 
a process.  (Facultative  planktont). 

Receptacles  7-8  /t  broad,  30-70  fi  long. 

Beasley  (ss),  Green  (1)  (ss).  Green  (2)  (cc),  Mill  (c).  North  Turtle  (rr), 
Oconomowoc  (cc).  Silver  (2)  (s).  Trout  (rr). 


Dinobryon  setularia  Ehrenberg.  PI.  13,  Fig.  13;  PI.  14,  Fig.  1. 

Abh.  d.  k.  Ak.  d.  Wiss.  Berlin  1833:  280.  1835;  Die  Infusionsthiercben  124, 
pi.  8,  fig.  8.  1838. 

Cells  in  free-floating,  densely  branching  colonies.  Receptacles  cylin- 
drical-campanulate,  with  the  convex  bases  tapering  abruptly  to  a sharp 
point.  Cells  with  shorter  and  broader  receptacles  than  the  other  species. 
Seasonal  variation  not  so  pronounced  as  in  other  species.  (Facultative 
Planktont) . 

Receptacles  10-14  ja  broad,  30^4  fi  long. 

Devils  (1)  (ccc),  Kawaguesaga  (ss).  Long  (4)  (ss).  Lost  (ss).  Lower 
Nemahbin  (ss).  Rock  (ss),  Round  (3)  (ss),  Winnebago  (rr). 


WISCONSIN  PHYTOPLANKTON 


75 


Dinobryon  divergens  Imhof.  PI.  14,  Fig.  2. 

Jahresbr.  d.  Naturf.  Ges.  Graubiindens  N.  P.  30:  134.  1887. 

Dinotryon  cylindricum  var.  divergens  (Imhof)  Lemmermann,  Ber.  d.  D.  Bot. 
Ges.  18:  517,  pZ.  19,  /Zfirs.  15-20.  1900. 

Cells  in  free-floating  densely  or  openly  branched  colonies.  Recep- 
tacles with  conical  bases  and  the  upper  portion  cylindrical  or  with 
slightly  flaring  mouths.  The  axis  of  the  upper  portion  of  receptacle 
forming  an  angle  of  45—90  degrees  with  that  of  the  basal  portion.  Sides 
of  receptacle  sometimes  undulate.  Seasonal  variation  confined  to  dense- 
ness of  branching  in  colony  rather  than  changes  in  receptacle  shape. 
(Facultative  Planktont). 

Receptacles  7-8  {x  broad,  35-50  ix  long  (2(4-27  p,  in  upper  portion  and 
15-20  in  basal  portion). 

Beasley  (s),  Boulder  (cc).  Browns  (cc),  Center  (ss).  Devils  (1)  (ss), 
Elizabeth  (cc),  George  (r).  Green  (2)  (rr).  Hill  (cc).  Lac  la  Belle  (ss), 
Long  (2)  (rr).  Marl  (ss),  Mary  (cc),  Meta  (r).  Mill  (cc),  Mud  (1)  (ss), 
Nagawicka  (cc).  North  Turtle  (ss),  Oconomowoc  (cc).  Otter  (ss).  Rock  (ss). 
Round  (4)  (rrr).  Silver  (2)  (cc),  Speese  (cc),  Tamarack  (ss),  Taylor  (ss), 
Tied  Canoe  (ss). 

HYALOBRYON  Lauterborn  1896. 

Cells  solitary  or  in  branching  colonies,  free-floating  or  epiphytic. 
Receptacle  shape  and  cell  contents  as  in  Dinobryon  but  with  the  wall 
of  the  receptacle  containing  a number  of  successive  growth  rings  instead 
of  homogeneous.  Wall  of  receptacle  more  delicate  than  Dmohryon. 

Hyalobryon  mucicola  (Lemmermann)  Pascher.  PL  14,  Figs.  3-4. 

D.  iSiisswasserfl.  Deutschl.,  osterr.  u.  d.  Schw.  2,  Plagellatae  2:  81,  fig.  131.  1913. 

Hyalohryon  Lauter'bornei  var.  mucicola  Lemmermann,  Ber.  d.  D.  bot.  Ges. 
19:  340.  1901;  Bachmann,  Arch.  f.  Hydrob.  u.  Planktonkde.  8:  81,  figs.  XP*- 
XI”.  1908. 

Cells  solitary,  epiphytic  upon  gelatinous  envelope  of  colonial  Myxo- 
phyceae,  Chlorophyceae  and  Phaeophyceae.  Receptacle  delicate,  upper 
portion  cylindrical  and  with  a flaring  mouth,  lower  portion  conical  and 
with  a short  stipe.  Growth  rings  of  receptacle  numerous.  Protoplast 
ovoid,  attached  to  base  of  receptacle,  with  two  golden-brown  chromato- 
phores,  two  cilia  of  unequal  length  and  an  eyespot.  (Euplanktont). 
Receptacles  4-6  ix  broad,  25-45  fx  long ; stipe  4-12  ix  long. 

Crawling  Stone  (r),  Lac  du  Flambeau  (sss),  Long  (3)  (c),  Mud  (2)  (rr), 
Round  (1)  (rr). 


76 


WISCONSIN  PHYTOPLANKTON 


Division  HYDRURINEAE. 

Cells  free-floating  or  sessile,  usually  in  palmella-like  colonies  and 
motile  only  at  the  time  of  reproduction;  rarely  solitary,  generally  in 
gelatinous  colonies  of  microscopic  to  macroscopic  size  that  have  a 
definite  to  indefinite  shape.  Colony  capable  of  growth  in  all  parts  or 
with  growing  region  restricted  to  apex.  Gelatinous  sheath  of  cells  hya- 
line, homogeneous  or  lamellated.  Cells  ovoid  to  spherical,  with  one  or 
two  golden-brown  parietal  chromatophores  and  with  or  without  a 
definite  wall. 

Reproduction  by  pyramidate,  spherical,  or  ovoid  zoospores  with  one 
or  two  cilia. 

The  members  of  this  division  are  the  connection  between  the  normally 
motile  and  the  highly  differentiated  sessile  Phaeophyceae. 

Order  PHAEO  CAPS  ALES. 

Cells  generally  organized  into  free-floating,  spherical,  ellipsoid,  or 
elongate  colonies.  Growth  of  colony  taking  place  in  all  parts  and  not 
restricted  to  the  apical  region.  Cells  variously  shaped  and  with  one  or 
two  golden-brown  chromatophores. 

Reproduction,  aside  from  vegetative  cell  division,  by  the  formation 
of  spherical  to  ovoid  zoospores. 

The  order  contains  the  single  family  of  the  Phaeocapsaceae  and  only 
one  member  of  the  family,  Phaeococcus,  is  found  in  the  local  flora. 

PHAEOCOCCUS  Borzi  1892. 

Cells  in  spherical,  ovoid,  or  irregularly  shaped  free-floating  colonies 
enclosed  by  a copious,  hyaline,  homogeneous  or  slightly  lamellated, 
gelatinous  envelope.  Cells  ellipsoid  to  sub-spherical  or  spherical.  Cell 
number  a multiple  of  two  in  young  colonies,  indefinite  in  older  colonies. 
Cells  containing  one  or  more  golden-brown  chromatophores,  sometimes 
with  a red  pigment  spot. 

Reproduction  by  vegetative  cell  division  or  direct  metamorphosis  of 
cell  contents  into  biciliate  ovoid  to  pyriform  zoospores. 

Phaeococcus  planctonicus  W.  & G.  S.  West.  PI.  14,  Fig.  6. 

Trans.  Roy.  Soc.  Edinb.  41;  496,  pi.  6,  figs.  15-16.  1905. 

Cells  spherical  to  sub-spherical,  generally  distributed  in  small  clumps 
within  a copious,  hyaline,  homogeneous  or  radially  fibrillar,  gelatinous 
envelope.  Number  of  cells  in  colony  generally  16-64.  Cells  contain- 


WISCONSIN  PHYTOPLANKTON 


'll 


ing  1-2  parietal,  disciform  to  bell-shaped,  golden-brown  chromatophores 
with  smooth  or  irregular  margins.  (Euplanktont). 

Cells  T.2-9.6  in  diam. ; colonies  50-250  ft  in  diam. 

Carson  (ss),  Clear  Crooked  (c),  Crawling  Stone  (rr),  Devils  (1)  (ss),  Hill- 
man (rr),  Jennie  (r),  Mary  (s),  Mendota  (sss),  Pokegama  (1)  (rr),  Sand 
(4)  (rr),  Shell  (ss),  Silver  (2)  (s).  White  Sand  (rr). 

Division  RHIZOCHRYSIDINAE. 

Algae  that  are  known  in  the  rhizopodial  stage  only,  although  the 
power  to  form  a motile  phase  is  presumed  to  be  present.  Cells  solitary 
or  in  small  colonies,  always  free-floating.  Cells  with  rhizopodial  pro- 
cesses and  with  or  without  a differentiated  periplast.  Cells  with  1-2 
golden-brown  chromatophores,  and  with  or  without  numerous  vacuoles. 

Reproduction  by  vegetative  cell  division. 

This  is  an  entirely  artificial  group  where  rhizopodial  forms  are  placed 
pending  further  elucidation  of  their  life  histories.  Since  the  group 
contains  such  doubtful  forms  no  attempt  has  been  made  to  differentiate 
the  orders  and  families. 

KEY  TO  THE  GENERA. 


Cells  solitary  or  in  irregular  colonies Rhizochrysis 

Cells  joined  in  a linear  series  to  form  colonies Chrysidastrum 


RHIZOCHRYSIS  Pascher  1913. 

Cells  free-floating,  solitary  or  in  colonies  that  are  naked  or  enclosed 
by  a gelatinous  sheath.  Cells  without  a differentiation  of  the  periplast 
but  with  few  or  numerous,  delicate,  pseudopodial  processes.  Cells  with 
one  or  two  golden-brown  chromatophores  and  numerous  vacuoles,  of 
small  size  when  united  in  colonies. 

Rhizochrysis  limnetica  sp.  nov.  PI.  14,  Fig.  6. 

Cells  solitary,  free-floating,  without  a differentiation  of  the  periplast 
but  with  numerous  spicule-like  processes  extending  in  all  directions. 
Cells  approximately  spherical,  with  one  golden-brown  chromatophore 
and  numerous  vacuoles.  (Euplanktont). 

Diam.  cells  (without  processes)  35-45  ft. 

Beasley  (sss),  Birch  Island  (rr),  Crawling  Stone  (rr),  Deer  (rr),  Diamond 
(rrr),  Half  Moon  (rr).  Horse  (rr),  Kitten  (sss),  Lac  du  Flambeau  (r).  Long 
(3)  (sss).  Marl  (rrr),  Nemahbin  (ss),  Oconomowoc  (rr),  Okauchee  (rrr), 


78 


WISCONSIN  PHYTOPLANKTON 


Otter  (rrr),  Pokegama  (2)  (r),  Rainbow  (1)  (r),  Round  (3)  (rr),  Sand  (4) 
(sss),  Taylor  (r),  Upper  Nashotah  (r),  Wildcat  (sss). 

This  species  is  quite  unlike  other  members  of  the  genus  since  the 
processes  are  much  more  delicate  and  the  cells  larger. 

CHRYSIDASTRUM  Lauterborn  1913. 

Cells  joined  to  one  another  by  pseudopodial  processes  and  arranged 
to  form  free-floating  linear  colonies  of  2-16  cells  that  are  not  enclosed 
by  a gelatinous  envelope.  Cells  spherical,  with  the  periplast  undiffer- 
entiated but  extending  into  several  long,  delicate,  pseudopodia-like  pro- 
cesses. Chromatophore  single,  central,  and  laminate  to  band-shaped. 

Reproduction  unknown. 

Chrysidastrum  catenatum  Lauterborn.  PI.  14,  Figs.  7-8. 

in  Pascher,  D.  Siisswasserfl.  Deutschl.,  dsterr.  u.  d.  Schw.  *2,  Flagellatae  2:  91, 
f.cj.  144.  1913. 

Specific  characters  the  same  as  those  of  the  genus.  (Euplanktont). 

Diam.  cells  (without  processes)  12-15  /a;  (with  processes)  45-60  fi. 

Kitten  (rr),  Mud  (2)  (rr),  Wildcat  (rrr). 

The  cell  shape  is  quite  like  that  of  Chrysamoeha  but  the  definite  or- 
ganization into  a linear  colony  and  the  single  laminate  chromatophore 
are  points  of  difference.  The  alga  should  also  be  compared  with  RMzo- 
chrysis  planctonica  Pascher. 


WISCONSIN  PHYTOPLANKTON 


79 


Class  HETEROKONTEAE. 

Cells  microscopic  or  macroscopic;  free-floating,  sessile,  or  epiphytic. 
Cell  shape  spherical,  ovoid,  pyriform,  cylindrical  or  irregular.  Cells 
solitary,  in  colonies  of  regular  to  irregular  shape,  or  united  to  form 
simple  filaments.  Colonies  or  individual  cells  with  or  without  a gelat- 
inous envelope.  Chromatophores  one  to  many,  parietal,  generally  disci- 
form, rarely  laminate,  yellowish- green  in  color  and  without  a pyrenoid. 
Assimilation  product  oil,  never  starch.  Cells  uninucleate  or  multinu- 
eleate. 

Asexual  reproduction  by  vegetative  cell  division  and  a formation  of 
zoospores.  Zoospores  ovoid  to  pyriform,  with  two  cilia  of  unequal 
length  and  generally  more  than  one  yellowish-green  chromatophore. 

Sexual  reproduction,  insofar  as  known,  isogamous,  by  zoogametes  that 
are  similar  in  structure  to  the  zoospores. 

The  various  genera  of  the  Heterokontae  were  formerly  scattered 
throughout  the  different  families  of  the  Chlorophyceae.  The  distinguish- 
ing characteristics  of  this  class  are  the  yellowish-green  chromatophores 
without  pyrenoids,  with  oil  not  starch  the  assimilation  product;  and 
zoospores  with  two  cilia  of  unequal  length.  There  are  three  orders  in 
the  class  and  representatives  of  all  three  are  found  in  Wisconsin  lakes. 

KEY  TO  THE  ORDERS. 


V'egetative  cells  motile Heteeochloridales 

Vegetative  cells  immobile. 

Cells  solitary  or  in  colonies,  never  in  filaments Heteeococcales 

Cells  united  to  form  simple  filaments Heteeotrichales 


Order  HETEROCHLORIDALES. 

Cells  solitary,  free-swimming,  ovoid  to  pyriform  in  shape.  Motile 
phase  dominant,  rarely  metamorphosing  over  into  an  amoeboid  or  pal- 
mella  phase.  Cells  with  two  cilia  of  unequal  length,  one  or  more  chro- 
matophores  of  a yellowish-green  color  and  without  an  eyespot.  Assimi- 
lation product  leucosin  or  fat,  never  starch. 

Asexual  reproduction  by  vegetative  division  of  cells. 

Sexual  reproduction  unknown. 

The  order  has  but  one  family,  the  Chloramoebaceae,  whose  characters 
are  those  of  the  order. 


80 


WISCONSIN  PHYTOPLANKTON 


CHLOROCHROMONAS  Lewis  1913. 

Cells  solitary,  generally  free-swimming,  very  rarely  amoeboid,  some- 
times attached  to  substratum  by  a posterior  pseudopodia-like  structure. 
Cell  shape  pyriform  to  sub-ovoid,  with  an  oblique  depression  at  the 
anterior  end.  Cilia  two,  at  the  anterior  end  of  the  cell  and  of  unequal 
length.  Chromatophores  two,  yellowish-green  in  color,  oblong  with 
rounded  ends  in  front  view,  somewhat  flattened  in  side  view.  Cells 
with  a single  anterior  vacuole,  one  nucleus,  and  without  an  eyespot. 
Nutrition  holophytic  or  saprophytic. 

Reproduction  by  longitudinal  fission  when  in  the  motile  phase. 

Chlorochromonas  minuta  Lewis.  PI.  15,  Figs.  1-3. 

Arch.  f.  Protistenkunde  32:  254,  ph  12,  figs.  1-24.  1913. 

Characters  as  described  above.  (Euplanktont). 

Cells  4.5-9.5  (av.  6.3)  p,  long,  with  an  average  breadth  of  4.7  p. 
Average  length  of  longer  cilium  12.5  p,  of  the  shorter  2.9  p. 

Mendota. 

This  organism  was  first  found  by  Lewis  in  a dish  containing  sections 
of  basswood  {Tilia  americana)  that  had  been  standing  for  some  time  in 
a dish  of  tap  water,  which  is  drawn  directly  from  Lake  Mendota.  I 
have  never  noted  the  alga  in  plankton  collections  but  have  no  doubt 
but  that  a continued  search  will  demonstrate  its  presence  in  Lake  Men- 
dota. During  the  past  winter  (1917-18)  the  alga  appeared  in  an  in- 
fusion of  fern  leaves  which  had  been  standing  for  some  time  in  tap 
w^ater.  This  shows  that  the  original  source  of  the  alga  was  the  water 
with  which  the  sections  were  moistened  and  not  the  Tilia. 

Order  HETEROCOCCALES. 

Cells  spherical,  ovoid,  saccate,  or  elongate  cylindrical ; solitary  or  in 
colonies  of  definite  or  indefinite  shape;  free-floating  or  sessile.  Cells 
of  colonies  embedded  in  a hyaline,  gelatinous  envelope  or  a tough  elastic 
membrane.  Chromatophores  one  to  many,  yellowish-green  to  nearly 
grass-green  in  color  and  with  oil  not  starch  the  assimilation  product. 

Asexual  reproduction  by  vegetative  cell  division  and  a formation  of 
zoospores  with  cilia  of  unequal  length. 

Sexual  reproduction  by  a fusion  of  zoogametes  that  are  similar  in 
stT'ucture  to  the  zoospores  is  known  in  certain  genera. 


WISCONSIN  PHYTOPLANKTON  81 

KEY  TO  THE  FAMILIES. 

Cells  epiphytic Chlobosaccaceab 

Cells  free-floating. 

Length  of  cells  several  times  the  diameter Ophiocytiaceae 

Length  of  cells  less  than  twice  the  diameter. 

Cells  irregularly  distributed  throughout  an  ovoid 

gelatinous  envelope Chlorobotrydaceae 

Cells  arranged  about  a common  center  within  an 

irregular  gelatinous  envelope Botryococcaceae 


Family  CHLOROSACCACEAE. 

Cells  epiphytic,  solitary,  gregarious,  or  embedded  in  an  amorphous 
gelatinous  matrix.  Chromatophores  one  to  several,  parietal,  of  a yel- 
lowish-green color,  with  oil  not  starch  the  assimilation  product. 

Asexual  reproduction  by  a formation  of  zoospores  that  presumably 
have  two  cilia  of  unequal  length. 

Sexual  reproduction  by  the  fusion  of  isogamous  zoogametes. 

PERONIELLA  Gobi  1887. 

Cells  epiphytic  upon  other  algae,  solitary  or  gregarious.  Shape  of 
mature  cells  globular  to  ovoid,  of  young  cells  pyriform  to  ovoid.  Cells 
attached  to  substratum  by  a delicate  hyaline  stipe  that  is  usually  some- 
what longer  than  the  cell.  Chromatophores  one  to  two,  pale  yellowish- 
green,  without  pyrenoids  or  starch  and  with  oil  as  the  assimilation 
product. 

Asexual  reproduction  by  the  division  of  cell  contents  into  2-4-8  uni- 
ciliate  ( ?)  zoospores  that  are  liberated  by  a lateral  rupture  of  mother 
cell  wall.  Zoospores  swarming  a short  time  and  then  coming  to  rest 
upon  substratum  and  developing  into  vegetative  cells. 

Peroniella  planctonica  G.  M.  Smith.  PI.  15,  Fig.  4. 

Bull.  Torr.  Bot.  Cl.  43:  476,  pi.  25,  M-  15.  1916. 

Cells  broadly  ovoid  to  pyriform,  with  a long,  delicate,  hyaline  stipe 
that  is  without  a disc  or  other  enlargement  at  the  base.  Chromato- 
phores usually  single,  rarely  two,  pale  yellowish-green,  without  pyre- 
noids or  starch.  (Euplanktont). 

Cells  (without  stipe)  6-9.5  /a  long;  (with  stipe)  15-18  /a.  Stipe  8-10  /a 
long,  1.2  /A  broad. 

In  gelatinous  envelope  of  SpJiaerozosma  filaments. 


Devils  (1)  (rr). 
6 


82 


WISCONSIN  PHYTOPLANKTON 


Family  CHLOROBOTRYDACEAE. 

Cells  solitary  or  in  free-floating  colonies  enclosed  by  a copious,  homo- 
geneous, gelatinous  envelope.  Colony  generally  with  a small  number 
of  cells  and  with  cell  number  a multiple  of  two.  Cells  spherical,  ovoid, 
angular,  or  cylindrical  j with  a firm  cell  wall  that  is  sometimes  impreg- 
nated with  a slight  trace  of  silica ; and  with  one  to  many  parietal,  disci- 
form, yellowish-green  chromatophores  without  pyrenoids. 

Asexual  reproduction  by  vegetative  cell  division  or  a formation  of 
zoospores  with  two  cilia  of  unequal  length. 

CHLOROBOTRYS  Bohlin  1901. 

Cells  rarely  solitary,  generally  in  colonies  of  2-4r-8-16  or  more  em- 
bedded in  a copious,  homogeneous,  hyaline,  gelatinous  envelope.  Cells 
spherical  to  broadly  ovoid,  with  a heavy  wall  that  sometimes  contains 
a small  amount  of  silica.  A conspicuous  red  pigment  spot  present  in 
cells  at  times. 

Reproduction  by  vegetative  division  of  cells  in  three  directions. 

KEY  TO  THE  SPECIES. 


Cells  ovoid,  with  few  chromatophores C.  Limneticus 

Cells  spherical,  with  numerous  chromatophores C.  Reguiabis 


Chlorobotrys  regularis  (W.  West)  Bohlin.  PI.  15,  Fig.  10. 

Bih.  kgl.  Sv.  Vet.-Ak.  Handl.  27,  Afd.  3,  No.  4:  34.  1901;  W.  & G.  S.  West, 
Jour,  of  Bot.  41 : 78,  pi.  447,  figs.  7-10.  1903. 

Chlorococcum  regulare  W.  West,  Jour.  Roy.  Micr.  Soc.  1892:  737,  pi.  10, 
fig.  55.  1892. 

Cells  spherical  to  subspherical ; rarely  solitary,  generally  in  colonies 
of  2-4-8-16  enclosed  by  a copious,  hyaline,  homogeneous,  gelatinous 
envelope.  Cell  wall  thick,  sometimes  containing  a trace  of  silica. 
Chromatophores  yellowish-green,  disciform,  parietal,  6-30  in  each  cell. 
Cells  at  times  containing  a single  conspicuous  red  pigment  spot.  (Ty- 
choplanktont). 

Diam.  cells  10-27  p.  Diam.  colonies  35-90  p. 

North  Turtle  (rrr). 

Chlorobotrys  limneticus  G.  M.  Smith.  PI.  15,  Fig.  9. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  653,  pi.  14,  fig.  10.  1918. 

Cells  ovoid,  irregularly  distributed  within  a homogeneous,  hyaline, 
gelatinous  envelope.  10-30  cells  in  a colony.  Chromatophores  3-4, 


WISCONSIN  PHYTOPLANKTON 


83 


pale  yellowish-green,  disciform,  parietal,  and  without  pyrenoids.  (Eu- 
planktont) . 

Cells  5-6  broad,  6-8  fx  long.  Diam.  colonies  40-200  /x. 

Camp  (rr). 

Family  BOTRYOCOCCACEAE. 

Cells  always  in  free-floating  colonies  of  deflnite  or  indefinite  shape. 
Number  of  cells  in  colony  generally  indefinite,  few  or  many.  Colony 
enclosed  by  an  envelope  that  may  be  hyaline  or  colored,  gelatinous  or 
leathery.  Cells  usually  ovoid,  rarely  spherical;  with  1-2  parietal, 
laminate  to  disciform,  yellowish-green  to  nearly  grass-green  chromato- 
phores  without  pyrenoids  and  with  oil  as  the  assimilation  product. 

Asexual  reproduction  by  vegetative  cell  division.  Zoospore  forma- 
tion or  sexual  reproduction  unknown. 

BOTRYOCOCCUS  Kiitzing  1849. 

Cells  in  free-floating  colonies  of  indefinite  shape.  Cells  closely  ap- 
posed to  one  another  and  enclosed  by  a gelatinous  or  tough  membrane 
that  is  sometimes  wrinkled  and  folded.  Colonies  generally  with  cells 
in  several  aggregates  that  are  connected  by  broad  or  delicate  strands 
of  the  colonial  integument.  Cell  shape  spherical,  ovoid,  or  cuneate. 
Groups  of  cells  arranged  in  a single  layer  around  a common  center,  or 
irregular  in  arrangement.  Chromatophore  single,  parietal,  laminate 
to  disciform,  yellowish-green  to  nearly  grass-green  in  color  and  without 
a pyrenoid. 

Reproduction  by  vegetative  division  of  cells. 

KEY  TO  THE  SPECIES. 

Cells  held  together  by  a thin  gelatinous  envelope B.  Sudeticus 

Cells  held  together  by  an  irregular  tough  membrane. 

Membrane  completely  enclosing  cells B.  BRAmm 

Membrane  covering  base  only  of  cells B.  Peotuberans  var.  Minor 

Botryococcus  sudeticus  Lemmermann.  PI.  15,  Fig.  8. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon.  4:  111,  figs.  6-7.  1896. 

Botryococcus  Braunii  G.  S.  West  non  Kiitzing,  Brit.  Freshw.  Algae  237,  figs. 
106A-106B.  1904;  G.  M.  Smith,  Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  545 

1916. 

Colonies  free-floating ; spherical  or  irregular ; with  cells  held  in  botry- 
oidal  clusters  by  a hyaline  gelatinous  envelope  and  frequently  joined 
10  one  another  by  broad  or  narrow  strands  of  the  gelatinous  envelope. 
Cells  spherical  to  subspherical,  16-32  or  more  in  each  botryoidal  group. 


84 


WISCONSIN  PHYTOPLANKTON 


and  arranged  around  a common  center.  Chromatophore  single,  cup- 
shaped to  disciform,  without  a pyrenoid.  (Euplanktont). 

Diam.  cells  6-13  fx. 

Clear  (rr),  Waubesa  (rrr). 

This  is  the  B.  Braunii  Ktz.  of  the  preliminary  list,  the  identification 
being  based  upon  G.  S.  West’s  description  of  B.  Braunii  in  his  British 
Freshwater  Algae.  Dr.  West  has  since  informed  me  that  the  Ineffigiata 
neglecta  of  that  work  is  B,  Braunii  Ktz.  and  the  B.  Braunii  described 
therein  is  B.  sudeticus  Lemm. 

Botryococcus  Braunii  Kiitzing.  PL  15,  Fig.  5. 

Species  algarum  892.  1849;  Presenius,  Abh.  Senckenb.  Naturf.  Ges.  2:  239, 
pi.  11,  figs.  27-33.  1858. 

Ineffigiata  neglecta  W.  & G.  S.  West,  Jour.  Roy.  Micr.  Soc.  1897:  503.  1897; 
Jour,  of  Bot.  41:  80,  pi.  447,  figs.  1-6.  1903. 

Cells  joined  in  small  free-floating  colonies  of  irregular  shape  that  are 
without  a conspicuous  gelatinous  envelope  but  completely  enclosed  by 
a tough,  elastic,  hyaline  to  orange  colored  membrane  that  is  pro- 
duced into  irregular  wrinkles,  folds,  and  spines.  Colonies  frequently 
united  to  form  compound  colonies  by  long  delicate  projections  of  the 
colonial  envelope.  Cells  ovoid  or  ellipsoid  in  shape  and  forming  a 
single  layer  around  a central  cavity.  Chromatophore  single,  cup-shaped 
to  laminate,  yellowish-green  to  nearly  grass-green  in  color,  without  a 
pyrenoid.  Assimilation  product  a reddish  oil  that  may  color  the  whole 
colony  a brick  red.  (Facultative  planktont). 

Cells  3.5-5.5  fx  broad,  5.7-10.5  fx  long.  Simple  colonies  up  to  100  g. 
in  diam. ; compound  colonies  up  to  1.5  mm. 

Balsam  (rr).  Bear  (3)  (rr).  Bear  Trap  (rrr),  Beaver  (2)  (rr),  Beaverdam 
(ss),  Birch  Island  (rrr),  Birch  (2)  (rr),  Boulder  (rrr).  Browns  (sss).  Camp 
(rrr),  Carson  (r).  Center  (r).  Chain  (rrr),  Chetac  (rr).  Clam  (rrr),  Clare 
(r),  Cochrane  (rrr).  Crawling  Stone  (rr).  Crooked  (sss).  Deer  (rr),  Delavan 
(rrr),  Des  Moines  (rr).  Devils  (1)  (r).  Devils  (2)  (r).  Devils  (3)  (rrr), 
East  (rr),  Elizabeth  (rr).  Green  (1)  (rr).  Green  (2)  (rrr).  Grindstone  (r). 
High  (rr).  Horse  (rrr).  Horseshoe  (1)  (rr),  Island  (rr),  Jennie  (rr),  Jones 
(rrr),  Kawaguesaga  (rrr),  Kegonsa  (r),  Kimball  (rrr).  Kitten  (rrr).  Lac 
Court  Oreilles  (sss).  Lac  du  Flambeau  (rrr),  Little  Bass  (1)  (rrr).  Little 
Butternut  (rrr).  Little  Crooked  (rrr).  Little  Doctor  (rr).  Little  Rice  (1)  (rr). 
Long  (1)  (rrr).  Lower  Nashotah  (r).  Lynx  (rr),  Mary  (sss),  Mendota  (ss), 
Mercer  (rrr).  Mill  (rrr),  Monona  (sss).  Mud  (3)  (rrr).  Mud  Hen  (sss),  Nancy 
(r),  Nicaboyne  (rrr).  No  Mans  (rr).  Paddock  (r).  Palmer  (rrr),  Pardee  (sss). 
Pike  (rrr),  Pokegama  (1)  (rrr),  Pokegama  (2)  (rrr).  Poor  Farm  (rrr).  Re- 
serve (rr).  Rice  (1)  (rr).  Round  (2)  (rrr),  St.  Croix  (rrr).  Sand  (1)  (r). 
Sand  (2)  (rr).  Sand  (3)  (rr),  Sand  (4)  (rrr),  Shell  (rr).  Silver  (2)  (r), 
Sishebogema  (rr).  South  Turtle  (rr).  Spirit  (rrr).  Tied  Canoe  (rrr),  Travis 
(rrr).  Upper  Nashotah  (sss),  Wapagossett  (rr),  Waubesa  (r).  White  Ash 
(rrr),  Whitefish  (rrr),  Wildcat  (rrr),  Winnebago  (rrr).  Wolf  (rrr). 


WISCONSIN  PHYTOPLANKTON 


85 


Botryococcus  protruberans  var.  minor  G.  M.  Smith.  PI.  15,  Figs.  6-7. 
Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19':  652,  pi.  14,  figs.  6-7.  1918. 

Cells  in  colonies  of  4-8-16  or  more  held  together  by  a tough  gelat- 
inous membrane.  Colonies  frequently  joined  to  one  another  by  long 
hyaline  strands  of  the  colonial  envelope.  Cells  ovoid  to  cuneate-ovoid, 
with  their  bases  embedded  in  the  colonial  envelope  and  their  apices 
not  enclosed  by  the  envelope.  Cells  arranged  in  a single  layer  around 
a central  cavity.  Chromatophores  single,  yellowish-green,  laminate, 
occupying  the  median  portion  of  the  cell.  (Euplanktont). 

Cells  8-9.5  /A  long,  5-6.5  fi  broad  at  the  widest  part. 

Diamond  (rrr),  George  (aa),  Hillman  (rr),  Lindy  (rr).  Oak  (ss),  Pardee 
(rr),  Sanford  (rr),  South  Crab  (s). 

This  species  is  distinguished  from  the  foregoing  by  the  smaller  num- 
ber of  cells  in  the  colony  and  the  projection  of  the  apex  of  the  cells 
through  the  colonial  integument. 

Family  OPHIOCYTIACEAE. 

Cells  sessile  or  free-floating,  solitary  or  colonial.  Length  of  cells 
generally  several  times  the  breadth.  Cells  straight,  curved,  sigmoid,  or 
spiral;  with  or  without  terminal  spines.  Chromatophores  yellowish- 
green  ; annular,  parietal  and  few  in  number ; or  disciform,  parietal  and 
numerous ; without  pyrenoids  and  with  oil  as  the  assimilation  product. 

Asexual  reproduction  by  division  of  cell  contents  to  form  4-16  aplano- 
spores  or  2-8  biciliate  zoospores  with  cilia  of  unequal  length. 

Sexual  reproduction  unknown. 

OPHIOCYTIUM  Nageli  1849. 

Cells  free-floating  or  epiphytic,  solitary  or  colonial ; straight,  arcuate, 
sigmoid,  or  spiral  elongate  cylinders  with  rounded  or  capitate  ends 
that  may  be  apiculate  or  attenuated  into  a single  spine.  Chromato- 
phores pale  yellowish-green,  H-shaped  in  optical  cross  section,  without 
pyrenoids  and  with  oil  as  the  assimilation  product.  Cells  coenocytic. 
Cell  wall  consisting  of  a homogeneous  cap  at  one  end  and  with  the  re- 
maining portion  of  the  wall  composed  of  a number  of  laminate  layers. 

Asexual  reproduction  by  division  of  cell  contents  to  form  4-16  aplano- 
spores  or  2-8  biciliate  zoospores  with  cilia  of  unequal  length. 


86 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 


Poles  of  cells  without  spines O.  Pabvulum 

Poles  of  cells  with  spines O.  Capitatum 


Ophiocytium  parvulum  (Perty)  A.  Braun.  PI.  15,  Fig.  11. 

Alg.  unicell.  55.  1855;  Lemmermann,  Hedwigia  38;  33,  pT.  4,  figs.  30-'33.  1899. 

Cells  cylindrical,  several  times  as  long  as  broad;  straight,  arcuate,  or 
spiral;  poles  rounded  and  without  spines.  Chromatophores  several, 
H-shaped  in  cross  section,  pale  yellowish-green.  Oil  droplets  rarely 
present.  ( Tychoplanktont) . 

Cells  3-9  fi  broad. 

Fishtrap  (rrr). 

Ophiocytium  capitatum  Wolle.  PI.  15,  Figs.  12-13. 

Freshw.  Algae  of  U.  S.  176,  pi.  158,  figs.  3-7.  1887. 

Cells  solitary ; arcuate,  sigmoid,  or  spiral  cylinders  with  poles  rounded 
and  the  same  size  as  or  slightly  larger  than  the  median  portion  of  the 
cell.  Length  of  cell  5-10  times  the  breadth.  Poles  of  cells  with  a 
single  short,  straight,  or  slightly  curved  spine.  (Tychoplanktont). 

Cells  5-10  /X  broad,  up  to  85  fx  long.  Spines  5-7  /x  long. 

Tied  Canoe  (rrr). 

var.  LONGiSPiNUM  (Mobius)  Lemmermann.  PI.  15,  Figs.  14^16. 
Hedwigia  38  : 32,  pi.  4,  figs.  21-25.  1899. 

Cells  cylindrical ; straight,  arcuate,  or  spirally  twisted,  with  a single 
long  spine  at  each  pole  that  is  nearly  as  long  as  the  cell.  (Euplank- 
tont). 

Diam.  cells  4.5-6  fx.  Length  of  spines  16-50  fx. 

George  (rr),  Loon  (rr). 

Order  HETEEOTRICHALES. 

Cells  in  simple,  unbranched  filaments;  with  or  without  a gelatinous 
envelope.  Cell  wall  firm,  fairly  thick,  lamellated  in  structure  and 
breaking  down  into  H-shaped  pieces  at  the  time  of  reproduction.  Chro- 
inatophores  few  to  several,  yellowish-green,  disciform,  and  parietal. 
Cells  usually  uninucleate.  Assimilation  product  oil,  not  starch. 

Asexual  reproduction  by  the  formation  of  aplanospores  or  by  zoo- 
spores with  two  cilia  of  unequal  length. 


WISCONSIN  PHYTOPLANKTON 


87 


Sexual  reproduction  by  the  fusion  of  isogamous  zoogametes. 

There  is  but  one  family  in  the  order,  the  Tribonemaceae,  whose  char- 
acters are  the  same  as  those  of  the  order. 

TRIBONEMA  Derbes  and  Solier  1856. 

Cells  in  simple  unbranched  filaments  destitute  of  an  enveloping  gelat- 
inous sheath.  Cells  cylindrical  or  barrel-shaped,  with  flattened  end 
walls.  Cell  wall  frequently  of  considerable  thickness  and  laminate  in 
structure.  Chromatophores  two  to  several,  yellowish-green,  disciform, 
parietal,  without  starch  and  with  oil  as  the  assimilation  product. 

Asexual  reproduction  by  aplanospores  and  biciliate  zoospores  that 
have  cilia  of  unequal  length.  The  cell  wall  pulling  apart  and  breaking 
down  into  H-shaped  pieces  at  the  time  of  reproduction. 

Sexual  reproduction  by  the  fusion  of  isogamous  zoogametes. 

Tribonema  minus  (Wille)  Hazen.  PI.  15,  Figs.  17-18. 

Mem.  Torr.  Bot.  Cl.  11:  185,  pi.  25,  figs.  7-8.  1902. 

Filaments  generally  forming  a floccose  yellowish  to  greenish  mass. 
Cells  cylindrical  or  slightly  swollen  in  the  median  portion,  generally 
2-4,  rarely  6,  times  as  long  as  broad.  Chromatophores  2-4,  yellowish- 
green,  disciform,  parietal,  generally  in  pairs.  (Facultative  planktont). 

Cells  5-6  /A  broad,  10-35  fi  long. 

Green  (1)  (rrr),  Mendota  (s). 

Members  of  this  genus  are  frequently  found  in  ditches  but  seldom  in 
lakes.  During  the  past  season  T.  minus  has  appeared  in  considerable 
quantity  in  the  plankton  of  Lake  Mendota,  although  previous  to  this 
time  the  alga  has  not  been  found  in  the  plankton.  A similar  sudden 
appearance  of  T.  homhycina  forma  depauperata  Wille,  a form  closely 
related  to  T.  minus,  has  been  noted  in  the  plankton  of  Danish  lakes  by 
Wesenberg-Lund  (Studier  over  de  danske  soers  Plankton  p.  100. 
Kjobenhavn,  1904). 


88 


WISCONSIN  PHYTOPLANKTON 


Class  CHLOROPHYCEAE. 

Cells  with  the  coloring  matter  restricted  to  definite  bodies  that  are 
grass-green  in  color  (chloroplasts).  Cells  free-floating,  sessile,  epi- 
phytic, epizootic,  or  endophytic ; solitary,  in  microscopic  to  macroscopic 
colonies  of  definite  or  indefinite  shape  that  are  naked  or  enclosed  by  a 
hyaline  to  colored,  homogeneous  or  lamellated,  firm  or  gelatinous  en- 
velope. Colonies  with  all  of  the  cells  morphologically  alike  or  differen- 
tiated. Colonies  growing  in  all  directions;  forming  simple,  laminated, 
or  parenchymatous  plates;  or  developing  into  simple  or  branched  fila- 
ments. Cells  motile  throughout  the  whole  life  history,  for  a portion 
of  it,  or  immobile  at  all  times.  Cells  variously  shaped ; spherical,  hemi- 
spherical, ovoid,  ellipsoid,  spindle-shaped,  acicular,  reniform,  angular, 
irregular,  cylindrical,  conical,  simple  to  branching  tubular,  or  con- 
stricted to  form  two  symmetrical  halves  of  various  shapes.  Cells  con- 
taining one  or  more  disciform,  laminate,  cup-shaped,  astral,  ribbon-like, 
or  reticulate  chloroplasts  that  are  parietal,  axial,  or  central  in  position 
and  have  one  or  more  centers  for  the  synthesizing  of  starch  (pyrenoids) . 
Assimilation  product  oil  in  a few  cases.  Cells  uninucleate  or  multinu- 
cleate  (coenocytic) ; containing  a central  vacuole,  numerous  small  vacu- 
oles, or  without  vacuoles.  Contractile  vacuoles  chiefly  confined  to  the 
motile  genera. 

Asexual  reproduction  by  vegetative  cell  division,  aplanospores,  zoo- 
spores, or  akinetes. 

Sexual  reproduction  by  isogamous  or  heterogamous  zoogametes,  isoga- 
mous  aplanogametes,  or  heterogamous  motile  antherozoids  and  immobile 
oospheres.  Zygotes  germinating  immediately,  or  after  a period  of  rest ; 
with  a direct  or  an  indirect  germination  into  the  plant  bod}". 

KEY  TO  THE  DIVISIONS 

Sexual  or  asexual  reproductive  bodies  with  2-4  cilia  of  equal  length. . I sokontak 
Sexual  or  asexual  reproduction  by  non-ciliate  reproductive  bodies Akontae 

Division  ISOKONTAE. 

Cells  solitary  or  in  colonies  and  showing  the  same  great  range  of 
variation  in  shape,  organization  of  the  colony,  interior  structure,  and 
method  of  reproduction  noted  in  the  description  of  the  class. 

Included  in  this  division  is  the  important  plankton  family  of  the 
Autosporaceae  where  no  motile  phase  of  reproduction  is  known.  The 


WISCONSIN  PHYTOPLANKTON 


89 


close  phylogenetic  connection  between  the  Autosporaceae  and  the  other 
members  of  the  Protococcales  is,  however,  perfectly  evident. 


KEY  TO  THE  ORDERS. 

Cilia  normally  present  throughout  the  whole  life  cycle Volvocalks 

Cilia  present  at  time  of  reproduction  only. 

Cells  in  simple  or  branched  filaments. 

Cells  uninucleate,  with  a single  laminate  chloroplast. . . .Ulotrichalxs 
Cells  multinucleate,  with  one  or  more  chloroplasts.  .Siphonooladiales 
Cells  solitary  or  in  simple  colonies,  generally  of  microscopic 

size Protococcales 


Order  VOLVOCALES. 

Cells  normally  ciliate  and  motile  during  the  vegetative  phases  of  the 
life  cycle.  Solitary  or  organized  into  colonies  of  definite  form  that 
generally  contain  a definite  number  of  cells.  Protoplasts  rarely  naked, 
usually  with  a differentiated  outer  cellulose  covering  that  may  be  par- 
tially gelatinized.  Shape  of  protoplast  spherical,  ovoid,  disciform, 
pyramidate,  or  irregularly  radiate.  Cells  with  a single  cup-shaped  to 
irregular  chloroplast,  with  or  without  pyrenoids ; with  2-4  cilia  at  the 
anterior  end;  generally  with  a disciform  to  bacilliform  eyespot,  two  to 
several  contractile  vacuoles,  and  one  nucleus.  Palmella  stages  fre- 
quently arising  in  the  unicellular  members. 

Asexual  reproduction  by  division  of  cell  contents  into  2-16  zoospores ; 
or  a development  of  special,  or  all  cells  of  the  colony  into  autocolonies. 

Sexual  reproduction  by  isogamous  zoogametes;  heterogamous  zoo- 
gametes; or  small  motile  antherozoids  and  large  immobile  oospheres. 

Many  hold  with  G.  S.  West  (Algae  151,  1916)  ^‘that  it  is  very  doubt- 
ful if  the  Volvocineae  have  sufficient  claims  to  be  removed  from  the 
Protococcales  and  elevated  to  a group  of  equal  rank  (the  ‘ Volvocales’) 
There  is  a very  close  relationship  between  the  ‘‘palmella^’  stage  of 
various  unicellular  Volvocales  and  the  family  Palmellaceae  of  the  Pro- 
tococcales. This  represents  to  me,  however,  a close  phylogenetic  rela- 
tionship between  the  two  and  not  a justification  for  uniting  in  the  same 
order  forms  with  mobile  vegetative  cells  and  those  which  are  immobile. 

KEY  TO  THE  FAMILIES. 

2 cilia  at  the  anterior  end  of  cells. 


Cells  solitary  CnLAMYDOMOif adaceae 

Cells  in  definite  coenobia  Volvocaceae 

4 cilia  at  the  anterior  end  of  cells Carteriaceae 


90 


WISCONSIN  PHYTOPLANKTON 


Family  CHLAMYDOMONADACEAE. 

Cells  normally  solitary  and  motile  during  the  vegetative  phases  of 
the  life  history.  Spherical,  ovoid,  cylindrical,  sub-acicular,  compressed, 
or  quadrately  projected.  Chloroplast  cup-shaped  to  laminate,  lateral 
or  posterior  in  position,  with  or  without  pyrenoids.  Cells  uninucleate, 
with  or  without  an  eyespot,  with  two  cilia  of  equal  length  that  generally 
have  two  contractile  vacuoles  at  their  base.  Cells  at  times  becoming 
immobile  and  developing  into  amorphous  colonies  enclosed  by  a wide 
gelatinous  envelope. 

Asexual  reproduction  by  the  division  of  cell  contents  to  form  2-16 
biciliate  zoogametes. 

Sexual  reproduction  by  the  fusion  of  isogamous  zoogametes. 

CHLAMYDOMONAS  Ehrenberg  1832. 

Cells  normally  solitary  and  motile ; though  capable  of  coming  to  rest, 
losing  the  cilia,  developing  a gelatinous  envelope  and  dividing  vegeta- 
tively  to  form  colonies  containing  an  indefinite  number  of  cells.  Cells 
spherical,  fusiform,  ovoid,  pyriform,  or  ellipsoid ; with  two  cilia  of  equal 
length  at  the  anterior  end.  Chloroplast  typically  cup-shaped,  posterior, 
and  with  one  pyrenoid.  Cells  uninucleate,  generally  with  two  con- 
tractile vacuoles  at  the  base  of  the  cilia;  with  or  without  an  eyespot 
which,  when  present,  lies  in  the  anterior  portion  of  the  cell. 

Asexual  reproduction  by  division  of  cell  contents  to  form  2-16  bicili- 
ate zoospores. 

Sexual  reproduction  isogamous,  by  the  division  of  cell  contents  into 
8-64  zoogametes  that  fuse  in  pairs  to  form  smooth-walled  or  sculptured 
zygotes. 


KEY  TO  THE  SPECIES. 


Cells  spherical. 

Anterior  end  without  a beak C.  Globosa 

Anterior  end  with  a pronounced  beak C.  Epiphytica 

Cells  ovoid. 

Chloroplast  cup-shaped  and  basal C.  Snowti 

Chloroplast  laminate,  lateral,  or  basal C.  Dhtobryonj 


Chlamydomonas  globosa  Snow.  PI.  16,  Fig.  8. 

Bull.  U.  S.  Fish  Comm.  22:  389,  pi.  1,  figs.  IIP-III®.  1903. 

Cells  spherical  or  slightly  ellipsoid,  without  an  anterior  beak.  Chloro- 
plast cup-shaped,  occupying  the  greater  portion  of  the  cell,  with  one 
pyrenoid  at  the  posterior  end.  Eyespot  present,  small,  generally  in  the 
middle  third  of  the  cell.  Cilia  slightly  longer  than  the  cell  and  with  a 


WISCONSIN  PHYTOPLANKTON 


91 


single  contractile  vacuole  at  their  base.  Palmella  stages  frequent  and 
usually  containing  4-8  cells.  (Euplanktont). 

Cells  5-10  fji  broad. 

Crawling  Stone  (rr). 

Chlamydomonas  epiphytica  sp.  nov.  PI.  16,  Figs.  11-13. 

Cells  spherical  to  pyriform,  with  a very  pronounced  anterior  beak. 
Chloroplast  cup-shaped,  forming  a thin  layer  next  to  the  cell  wall,  with 
a single  pyrenoid  at  the  posterior  end.  Eyespot  conspicuous,  disciform, 
at  the  anterior  end  of  the  cell.  Cilia  more  than  twice  as  long  as  the 
cell.  Cells  frequently  coming  to  rest  in  the  gelatinous  envelope  of 
Microcystis  colonies  but  not  losing  the  eyespot  and  usually  retaining 
the  cilia.  (Euplanktont). 

Cells  7-8  broad,  8-9  fi  long ; cilia  20-25  fi  long. 

Elizabeth  (s),  Mary  (sss). 

The  alga  is  frequently  found  in  the  gelatinous  envelope  of  Microcystis 
colonies  and  suggests  an  epiphytic  CJiaracmm  but  the  presence  of  cilia 
shows  that  it  is  a ChlaniydomoTias. 

Chlamydomonas  Snowh  Printz.  PI.  16,  Figs.  9-10. 

Skr.  Vidensk.-Selsk.  i Kristiana,  Mat.-Naturv.  Kl.  1913':  No.  6:  18.  1914. 

Chlamydomonas  communis  Snow,  Bull.  U.  S.  Fish  Comm.  22:  388,  pi.  1, 
figs.  ir-IP.  1903. 

Cells  motile  but  frequently  forming  palmella  stages  containing  a 
considerable  number  of  cells.  Cell  shape  ovoid  to  ellipsoid,  with  a very 
inconspicuous  anterior  beak.  Chloroplast  cup-shaped,  massive  in  the 
posterior  portion,  with  one  pyrenoid  at  the  center  of  the  cell.  Cilia 
slightly  longer  than  the  cell;  eyespot  inconspicuous,  variable  in  posi- 
tion. (Facultative  planktont). 

Cells  6.5-8  fi  broad,  10-15  y.  long. 

Nancy  (rr). 

Chlamydomonas  dinobryoni  sp.  nov.  PI.  16,  Pigs.  5-7. 

Cells  rarely  free-swimming,  generally  in  large  numbers  and  filling 
the  empty  receptacles  of  Dinohryon  colonies.  Cells  small,  ovoid  to  pyri- 
form in  shape,  without  an  anterior  beak;  with  two  short  cilia  at  the 
anterior  end.  Chloroplast  disciform  to  hemispherical,  basal  or  lateral 
in  position,  containing  a p3rrenoid.  Eyespot  and  contractile  vacuoles 
not  observed.  (Euplanktont). 

Cells  2-3  y broad,  3.5-5  y long;  cilia  6-8  y long. 

Lac  du  Flambeau  (ss),  Long  (3)  (s),  Pokegama  (2)  (r). 


92 


WISCONSIN  PHYTOPLANKTON 


Many  of  the  empty  Dinohryon  receptacles  in  these  three  connecting 
lakes  were  filled  with  a minute  green  organism.  These  had  cilia,  even 
when  in  the  receptacle,  and  on  the  slightest  crushing  of  the  receptacle 
began  swimming  around  outside  of  it.  Since  cilia  are  constantly  pres- 
ent the  alga  is  a CMamydomonas  and  not  one  of  the  Palmellaceae  col- 
lected at  the  time  of  reproduction. 

Family  CARTERIACEAE. 

Cells  normally  motile  and  with  four  cilia  of  equal  length  at  the  an- 
terior end.  Solitary,  or  in  coenobia  containing  a definite  number  of 
cells.  Cell  shape  spherical,  ovoid,  ellipsoid,  cardioid,  pyriform,  or 
lenticular.  Cells  enclosed  by  a definite  wall,  and  with  or  without  a 
cup-shaped  to  lenticular  chloroplast  that  is  with  or  without  pyrenoids. 
Eyespot  generally  present,  conspicuous,  and  at  the  anterior  end  of  the 
cell.  Cells  frequently  with  contractile  vacuoles  at  the  base  of  the 
cilia.  Palmella  stages  known  in  the  solitary  members  of  the  family. 

Asexual  reproduction  by  the  division  of  cell  contents  into  2-16  tetra- 
ciliate  zoospores  or  into  autocolonies. 

Sexual  reproduction  isogamous,  by  a fusion  of  tetraciliate  zoogametes. 

CARTERIA  Diesing  1866. 

Cells  solitary,  generally  motile  throughout  the  vegetative  phases  of 
the  life  cycle.  Spherical,  ovoid,  ellipsoid,  or  cardioid  in  shape;  with 
four  cilia  of  equal  length  at  the  anterior  end.  Cell  contents  consisting 
of  a single  cup-shaped  chloroplast  that  contains  a pyrenoid;  one  eye- 
spot;  and  two  contractile  vacuoles  at  the  base  of  the  cilia.  Palmella 
stages  containing  an  indefinite  number  of  cells  are  found  at  times. 

Asexual  reproduction  by  division  of  cell  contents  to  form  2-8  tetra- 
eiliate  zoospores. 

Sexual  reproduction  by  the  division  of  cell  contents  to  form  4-64 
tetraciliate  zoogametes  that  fuse  in  pairs  to  form  zygotes  with  smooth 
or  sculptured  walls. 


KEY  TO  THE  SPECIES. 

Cells  ellipsoid C.  Klebsh 

Cells  cardioid C.  Cobdiformis 

Carteria  cordiformis  (Carter)  Diesing.  PI.  16,  Fig.  1. 

Sitzbr.  d.  k.  Ak.  d.  Wiss.  Wien,  Mat.-Naturw.  Kl.  52?:  356.  1866;  Dill,  Jahrb.  f. 
wlss.  Bot.  28  : 353,  pi.  5,  figs.  42-44.  1895. 

Cells  cardioid  in  shape  with  four  cilia  at  the  base  of  the  apical  de- 
pression. Chloroplast  cup-shaped,  fairly  massive,  with  a single  pyre- 


WIBC0N8IN  PHYTOPLANKTON 


93 


noid  in  the  posterior  region.  Cells  with  two  contractile  vacuoles  at 
the  base  of  the  cilia  and  with  a disciform  eyespot  in  the  upper  third 
of  the  cell.  (Tychoplanktont). 

Cells  9-16  broad,  12-20  /t  long. 

Crawling  Stone  (rrr). 

Carteria  Klebsii  (Dangeard)  Dill.  PI.  16,  Figs.  2-4. 

Jahrb.  f.  wiss.  Bot.  28  : 353.  1895;  Printz,  Skr.  Vidensk.-Selsk.  Kristiana,  Mat.- 
Naturv.  Kl.  1913':  No.  6:  13.  1914. 

Pithiscus  Klebsii  Dangeard,  Ann.  Sci.  Nat.  7 Ser.  Bot.  7:  137,  pi.  12,  figs. 
1-6.  1888. 

Cells  solitary,  ellipsoid  to  ellipsoid-cylindrical,  Avith  a more  or  less 
prominent  beak  at  the  anterior  end.  Chloroplast  cup-shaped,  massive, 
with  a large  pyrenoid  at  the  posterior  end.  Cells  without  an  eye-spot 
and  with  two  contractile  vacuoles  at  the  base  of  the  cilia.  Cilia  about 
twice  as  long  as  the  cells.  Palmella  stages  containing  many  cells  at 
times.  ( Tychoplanktont ) . 

Cells  5-10  fi  broad,  8-16  fi  long. 

Pokegama  (1)  (r). 


Family  VOLVOCACEAE. 

Cells  always  motile  and  in  coenobia  of  definite  shape  that  contain  a 
definite  or  an  indefinite  number  of  cells.  Colonies  enclosed  in  a homo- 
geneous, hyaline,  gelatinous  envelope.  Cells  of  colony  all  alike  or  dif- 
ferentiated into  vegetative  and  reproductive  cells.  Vegetative  cells 
spherical,  ellipsoid,  pyriform  or  disciform ; with  or  without  connecting 
cytoplasmic  processes;  always  biciliate.  Chloroplasts  generally  cup- 
shaped and  containing  one  pyrenoid.  Vegetative  cells  usually  with  an 
eyespot  and  two  contractile  vacuoles. 

Asexual  reproduction  by  the  division  of  all  or  certain  of  the  cells  in 
the  colony  to  form  autocolonies. 

Sexual  reproduction  by  a division  of  all  cells  in  the  colony  to  form 
isogamous  zoogametes  or  heterogamous  zoogametes  of  slightly  different 
size;  or  the  formation  of  motile  antherozoids  from  certain  cells  and 
large  immobile  oospheres  from  others.  Zygotes  with  smooth  or  sculp- 
tured walls. 


94: 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  GENERA. 


Colony  with  cells  in  a flat  plate Gonitjm 

Colony  with  cells  forming  a hollow  sphere. 

Cells  mutually  compressed Pandobina 

Cells  some  distance  from  one  another. 

Asexual  reproduction  by  division  of  all  cells  in  colony Eudobina 

Asexual  reproduction  by  division  of  special  cells. 

At  least  half  of  cells  capable  of  forming  autocolonies. . .PLEonoEmA 
Only  a few  cells  capable  of  forming  autocolonies Volvox 


GONIUM  Mueller  1773. 

Colonies  of  4^8-16  cells  arranged  in  a flat  quadrangular  plate  and 
embedded  in  a common  gelatinous  matrix  or  connected  by  broad  gelat- 
inous strands.  Cells  ovoid  to  pyriform,  with  a single  cup-shaped  chlor- 
oplast  containing  one  pyrenoid.  Each  cell  with  two  cilia  of  equal 
length,  contractile  vacuoles  at  the  base  of  the  cilia,  and  an  eyespot. 
Four-  and  eight-celled  colonies  with  the  cilia  on  the  same  side ; sixteen- 
celled  colonies  with  the  four  central  cells  having  their  cilia  on  the  same 
side  and  the  twelve  marginal  cells  with  radially  arranged  cilia. 

Asexual  reproduction  by  simultaneous  division  of  all  cells  in  the 
colony  to  form  autocolonies,  or  by  a formation  of  2-4  zoospores  in  each 
cell. 

Sexual  reproduction  isogamous,  by  a fusion  of  biciliate  zoogametes. 

Gonium  pectorals  Mueller.  PI.  16,  Figs.  14-15. 

Vermium  terrestrium  et  fluviatilium  etc.  1:  60.  1773;  Migula,  Bot.  Cent.  44: 

72,  pi.  2,  figs.  1-8.  1890;  Harper,  Trans. -Am.  Micr.  Soc.  31:  65,  pi.  5,  figs.  1-19, 
23.  1912. 

Colonies  containing  4-8-16  cells.  Usually  with  16  cells  arranged  in 
two  concentric  series  in  a flat  plate  with  truncate  corners.  Cells  con- 
nected with  one  another  by  broad,  hyaline,  gelatinous  processes  and 
with  open  spaces  between  the  processes;  or  with  processes  indistinct 
and  the  whole  colony  embedded  in  a homogeneous,  gelatinous  matrix. 
Outer  ring  with  twelve  cells  whose  long  axes  lie  parallel  to  the  plane 
of  the  coenobe.  Inner  ring  of  four  cells  with  a large  open  space  at  the 
center  and  their  long  axes  perpendicular  to  plane  of  the  coenobe.  Cells 
ovoid  to  pyriform,  with  two  cilia  at  the  anterior  end ; a posterior  massive 
cup-shaped  chloroplast ; an  anterior  eyespot ; and  two  contractile  vacu- 
oles at  the  base  of  the  cilia.  (Tychoplanktont) . 

Cells  7-11  fjL  broad,  10-25  fi  long. 

Beaverdam  (rrr),  Clam  (rrr),  Duck  (rr),  Fowler  (rrr),  Island  (r),  K»- 
consa  (rrr),  Long  (1)  (rrr),  Mendota  (rrr),  Number  One  (rr).  Pike  (rrr), 
Poplar  (rrr). 


WISCONSIN  PHYTOPLANKTON 


9S 


PANDORINA  Bory  1824. 

Colonies  always  motile,  spherical  to  snbspherical,  containing  4-8-16- 
32  cells  mutually  compressed  to  form  a hollow  sphere  with  a small 
open  space  at  the  center.  Colony  enclosed  by  a fairly  copious,  firm, 
hyaline,  homogeneous,  gelatinous  envelope.  Cells  pyriform  to  angular 
by  mutual  compression,  with  pointed  ends  toward  the  center  of  the 
colony;  biciliate  at  the  fiattened  distal  end,  the  two  cilia  lying  close 
together  while  passing  through  the  colonial  envelope  and  then  becom- 
ing markedly  divergent.  Chloroplast  single,  massive,  cup-shaped,  with 
one  pyrenoid  at  the  base.  Eyespot  single,  generally  on  distal  face  of 
the  cell.  Cells  with  a definite  wall  and  two  contractile  vacuoles  at  the 
base  of  the  cilia. 

Asexual  reproduction  by  simultaneous  division  of  all  cells  of  the 
colony  to  form  autocolonies  that  are  liberated  by  a gelatinization  of  the 
colonial  envelope. 

Sexual  reproduction  by  a division  of  each  cell  of  the  colony  into 
16-32  zoogametes.  Zoogametes  showing  indications  of  heterogamy  in 
the  slight  difference  in  size  and  motility  of  the  pairs  that  fuse  to  form 
the  smooth  walled  zygote. 

Pandorina  morum  Bory.  PI.  16,  Figs.  16-17. 

Encyc.  meth.  hist.  nat.  de  Zoophytes  2:  600.  1824;  G.  S.  West,  Brit.  Freshw. 
Algae  193,  figs.  76a-76h.  1904. 

Colonies  generally  16-celled  and  as  described  above.  (Facultative 
Planktont) . 

Cells  8-16  fx  broad ; colonies  20-^5  ju,  broad. 

Bear  Trap  (rrr),  Blake  (rrr),  Camp  (rr),  Center  (cc),  Chetac  (rr),  Chetek 
(ss).  Deer  (rrr)/.  Duck  (ss).  East  (rrr),  Fowler  (rr).  Grindstone  (s),  Hillman 
(rr).  Hooker  (s),  Kegonsa  (sss).  Lac  Court  Oreilles  (ss),  Lindy  (rr).  Little 
Bass  (2)  (rr).  Little  Butternut  (rr).  Little  Rice  (1)  (r).  Little  Wood  (rrr). 
Long  (1)  (rrr),  Loveless  (rr),  Lower  Nashotah  (rr).  Lower  Nemahbin  (rr). 
Lower  Turtle  (sss),  Mendota  (ss),  Monona  (s).  Mud  (1)  (rrr),  Nagawicka 
(as),  Nicaboyne  (r),  No  Mans  (rr),  Number  One  (rr),  Oconomowoc  (rrr), 
Okauchee  (rrr),  Pokegama  (3)  (r).  Prairie  (r).  Rice  (1)  (r),  St.  Croix  (rr), 
Sishebogema  (rr).  South  Turtle  (sss),  Upper  Nashotah  (rr),, Upper  Nemahbin 
(rr).  Upper  Turtle  (rr),  Waubesa  (ss),  Whitefish  (rr),  Winnebago  (rr). 

EUDORINA  Ehrenberg  1832. 

Colonies  always  motile,  spherical  or  slightly  elongate,  of  16-32-64 
cells  lying  some  distance  from  one  another  and  arranged  to  form  a 
hollow  sphere  near  the  periphery  of  the  homogeneous,  hyaline,  gelat- 
inous envelope.  Cells  spherical,  with  or  without  a beak  at  the  point 
of  origin  of  the  two  cilia.  Cilia  parallel  while  passing  through  the 


96 


WISCONSIN  PHYTOPLANKTON 


colonial  envelope  and  then  widely  divergent.  Chloroplast  single,  cup- 
shaped, filling  practically  the  whole  cell  and  generally  with  several  pyre- 
noids.  Cells  with  a firm  wall,  one  or  two  anterior  contractile  vacuoles, 
and  a single  conspicuous  eyespot  near  the  base  of  the  cilia. 

Asexual  reproduction  by  a simultaneous  division  of  all  cells  to  form 
autocolonies  which  are  liberated  by  a rupture  of  the  colonial  envelope. 

Sexual  reproduction  heterogamous,  dioecious,  with  all  cells  of  a col- 
ony developing  into  large  immobile  oospheres  or  plate-like  masses  of 
32-64  fusiform  antherozoids ; or  monoecious  with  four  cells  forming 
antherozoids  and  the  remainder  oospheres.  Zygote  smooth-walled. 

Eudorina  elegans  Ehrenberg.  PI.  19,  Pig.  1. 

Abh.  d.  kgl.  Ak.  d.  Wiss.  zu  Berlin  1831:  78,  pi.  2,  10j^-10d.  1832;  G.  S. 

West  Brit.  Freshw.  Algae  194,  figs.  77a-77f.  1904. 

Colonies  generally  32-celled  and  as  described  above.  (Facultative 
planktont) . 

Cells  12-24  jx  in  diam. ; colonies  50-200  fi  in  diam. 

Balsam  (rrr),  Bear  (3)  (ss),  Bear  Trap  (r),  Beaverdam  (sss).  Big  Butter- 
nut (rr),  Birch  (2)  (ss),  Birch  Islanjd  (rr),  Boulder  (cc),  Bryer  (rr).  Camp 
(cc),  Catherine  (ss).  Center  (sss),  Chetac  (ss),  Chetek  (s),  Clam  (rr),  Crawl- 
ing Stone  (rrr),  Delavan  (sss).  Devils  (1)  (aa).  Diamond  (sss),  Duck  (ss), 
Dunham  (ss),  Dutchmans  (rrr),  Elizabeth  (rr).  Pish  (sss),  Fowler  (rr). 
Granite  (ss).  Green  (2)  (rr),  Grindstone  (rrr),  Hillman  (rr).  Hill  (rrr). 
Hooker  (rr).  Horseshoe  (1)  (rr).  Horseshoe  (2)  (rrr),  Howey  (rrr).  Island 
(ss),  Jennie  (r),  Kawaguesaga  (rr),  Kegonsa  (ss).  Lac  Court  Oreilles  (rr). 
Lac  la  Belle  (rr).  Lake  of  the  Woods  (S),  Lindy  (rr).  Little  Butternut  (rr). 
Little  Wood  (rrr).  Long  (3)  (rrr).  Loon  (rr).  Lower  Nemahbin  (rrr).  Lower 
Turtle  (r).  Lynx  (rr),  Meronk  (rrr).  Middle  McKenzie  (rr),  Nancy  (rr), 
Nicaboyne  (ss),  No  Mans  (rr).  North  Turtle  (ss).  North  Twin  (rr).  Number 
One  (rr),  Okauchee  (rr).  Paddock  (cc).  Pine  (2)  (rrr).  Pike  (r),  Pokegama 
(2)  (rr),  Pokegama  (3)  (ss).  Poplar  (rr).  Prairie  (ss).  Reserve  (rr).  Rain- 
bow (rrr).  Rice  (1)  (ss),  Rooney  (rr).  Round  (1)  (r).  Round  (2)  (rr). 
Round  (3)  (sss).  Sand  (1)  (sss).  Sand  (4)  (rr).  Silver  (2)  (c),  Sishebogema 
(ss).  South  Crab  (rr).  South  Turtle  (sss).  Spirit  (sss).  Squirrel  (ss),  Tender- 
foot (rrr),  Travis  (rrr).  Vermilion  (rr),  Waubesa  (sss).  White  Sand  (rrr). 

PLEODORINA  Shaw  1894. 

Colonies  always  motile;  spherical  to  sub-spherical,  with  32-128  cells 
lying  some  distance  from  one  another  just  within  the  periphery  of  the 
homogeneous,  hyaline,  gelatinous,  colonial  envelope  and  not  connected 
by  cytoplasmic  strands.  Cells  differentiated  into  those  that  are  purely 
vegetative  in  character  and  those  capable  of  dividing  to  form  daughter 
colonies.  All  but  four  cells  of  the  colony  reproductive  or  about  half 
reproductive  and  half  vegetative.  Cells  spherical  to  ovoid  in  shape. 
Vegetative  cells  with  a cup-shaped  chloroplast  containing  one  pyrenoid; 


WISCONSIN  PHYTOPLANKTON 


97 


a large  anterior  eyespot ; two  cilia  of  equal  length,  with  two  contractile 
vacuoles  at  their  base.  Reproductive  cells  at  first  like  the  vegetative 
cells,  later  with  a more  massive  chloroplast  that  eventually  contains 
several  pyrenoids.  The  eyespot  and  cilia  of  reproductive  cells  disap- 
pearing when  they  are  mature. 

Asexual  reproduction  by  a simultaneous  division  of  all  reproductive 
cells  to  form  autocolonies. 

Sexual  reproduction  (which  has  been  observed  in  one  species  only) 
heterogamous,  dioecious,  by  a division  of  all  reproductive  cells  to  form 
plates  of  64-128  biciliate,  fusiform  antherozoids ; or  a development  of 
reproductive  cells  into  oospheres.  Zygotes  smooth-walled. 

The  validity  of  this  genus  has  been  questioned  by  many  and  the  view 
put  forward  that  the  alga  is  but  a stage  in  the  life  history  of  Eudorina. 
Grove  (New  Phytol.  14;  169-182.  1915)  gives  a full  discussion  of  the 
literature  of  Pleodorina.  Although  Eudorina  elegans  is  found  in  a 
large  number  of  Wisconsin  lakes,  Pleodorina  has  been  found  in  but 
three  of  them.  If  Pleodorina  is  a developmental  stage  of  Eudorina,  it 
is  strange  that  the  ‘‘Pleodorina^’  stage  has  not  been  observed  with 
greater  frequency.  The  young  colonies  look  very  much  like  those  of 
Eudorina  and  it  is  probably  on  this  account  that  the  two  have  been 
confused. 


Pleodorina  californica  Shaw.  PI.  17,  Figs.  1-3. 

Bot.  Gaz.  19:  279,  pi.  27,  figs.  1-9.  1894. 

Colonies  containing  64-128  cells.  Cells  usually  spherical  and  about 
half  vegetative  and  half  reproductive.  Reproductive  cells  becoming 
4-5  times  broader  than  the  vegetative  cells.  (Facultative  planktont). 

Vegetative  cells  6-14  fi  in  diam. ; reproductive  cells  6-34  p.  in  diam. 
Colonies  40-400  p in  diam. 

Clam  (ss).  Mud  (1)  (cc).  Sand  (1)  (r). 

VOLVOX  L.  1758. 

Colonies  always  motile,  spherical  to  ovoid,  containing  a large  number 
of  cells  arranged  in  a single  layer  just  within  the  periphery  of  the 
homogeneous,  hyaline,  gelatinous,  colonial  envelope.  Cells  differen- 
tiated into  those  for  vegetative  purposes,  asexual,  and  sexual  repro- 
duction. Vegetative  cells  close  together  or  some  distance  from  one 
another,  with  or  without  cytoplasmic  connections  of  varying  thickness. 
Cell  shape  spherical,  ovoid,  or  disciform.  Individual  cells  or  groups 
of  cells  sometimes  enclosed  by  their  own  gelatinous  envelope.  Celk 
with  two  cilia  of  equal  length,  2-6  contractile  vacuoles,  one  nucleus. 


7 


98 


WISCONSIN  PHYTOPLANKTON 


one  eyespot,  and  a cup-shaped  to  disciform  chloroplast  that  contains 
one  pyrenoid.  Number  of  cells  in  a colony  varying  from  200-22,000. 

Asexual  reproductive  cells  few  in  number  (rarely  more  than  20)  and 
forming  autocolonies  by  repeated  division,  the  young  colonies  migrat- 
ing to  the  center  of  the  coenobe  at  a certain  stage  in  their  development. 

Sexual  reproduction  heterogamous,  monoecious  or  dioecious,  with  a 
development  of  6-400  cells  into  spherical  oospheres  and  few  or  many 
of  the  cells  into  antheridia  that  contain  16-256  biciliate  fusiform  anther- 
ozoids.  Zygote  with  a smooth  or  stellate  wall. 

KEY  TO  THE  SPECIES. 


Cells  with  cytoplasmic  connections. 

Cytoplasmic  connections  heavy V.  Globator 

Cytoplasmic  connections  delicate V.  Aureus 

Cells  without  cytoplasmic  connections V.  Mononae 


VOLVOX  GLOBATOR  L.  PI.  18,  Figs.  3-5. 

Systema  natura,  Ed.  10:  820.  1758;  Cohn,  Beitr.  z.  Biol.  d.  Pflanzen  1,  Heft  3: 
93,  vl.  2,  -figs.  1-6.  1875. 

'Colonies  large,  with  many  (1,000-22,000)  cells  that  are  flattened  and 
pentagonal  to  octagonal  in  surface  view.  Cells  connected  to  one  an- 
other by  stout  cytoplasmic  strands.  Chloroplast  of  cells  single,  flat- 
tened and  angular,  with  one  pyrenoid.  Cells  with  2-6  contractile  vacu- 
oles at  the  base  of  the  two  cilia  and  with  an  eyespot.  Gelatinous  sheaths 
of  individual  cells  sharply  defined  and  (in  surface  view)  pentagonal 
to  octagonal  by  mutual  compression.  Generally  with  8 asexual  repro- 
ductive cells  giving  rise  to  autocolonies.  Colonies  commonly  monoe- 
cious, with  12-40  (generally  20-30)  oospheres  enclosed  by  large  gelat- 
inous vesicles.  Antherids  a flat  plate  of  64-256  fusiform  antherozoids 
with  laterally  attached  cilia.  Zygote  verrucose,  with  conical  warts. 
( Tychoplanktont) . 

Cells  2-7.5  (generally  3-5)  /a  in  diam.  Colonies  400-800  ^ in  diam. 

Center  (s).  Hooker  (rr),  Kegonsa  (rr),  Monona  (r).  Soft  (rrr),  Wauhesa 
(rrr). 


VoLvox  AUREUS  Ehrenberg.  PI.  18,  Fig.  2. 

Die  Infusionsthierchen  71,  pi.  4,  fig.  2.  1838;  Klein,  Jarhb.  f.  wiss.  Bot.  20: 
138,  pi.  12,  figs.  26-33.  1889. 

Colonies  spherical,  containing  a comparatively  small  (200-4,000) 
number  of  cells.  Cells  circular  in  surface  view,  connected  with  one 
another  by  very  fine  cytoplasmic  strands.  Individual  gelatinous  sheaths 
of  cells  confluent  with  the  colonial  envelope.  Cells  containing  a spheri- 


WISCONSIN  PHYTOPLANKTON 


99 


eal  chloroplast,  one  eyespot,  and  a pair  of  contractile  vacuoles  at  the 
base  of  the  two  cilia.  4-14  asexual  reproductive  cells  giving  rise  to 
autocolonies.  Colonies  generally  dioecious,  with  3-9  oospheres  and 
about  half  of  the  cells  developing  into  antherids  that  contain  16-32 
fusiform  antherozoids  with  two  terminal  cilia.  Zygote  smooth-walled. 
(Facultative  Planktont). 

Cells  5-9  fi  in  diam. ; colonies  200-680  in  diam. 

Beaverdam  (rrr),  Camp  (sss),  Center  (ss),  Delavan  (ss),  Eagle  (rr),  Eliza- 
beth (rrr),  Fowler  (rrr),  Jennie  (rrr),  Kawaguesaga  (rrr),  Lac  du  Flam- 
beau (rr).  Lac  la  Belle  (rr).  Mill  (rrr),  Oconomowoc  (rrr).  Paddock  (r), 
Pokegama  (1)  (rr),  St.  Croix  (rrr).  Silver  (2)  (rr). 

' Volvox  mononae  sp.  nov.  PI.  18,  Fig.  1. 

Colonies  spherical,  containing  a comparatively  small  (400-2500) 
number  of  cells.  Cells  spherical,  not  connected  with  one  another  by 
cytoplasmic  processes.  Individual  sheaths  of  cells  confluent  with  colon- 
ial envelope.  Cells  containing  a single  bell-shaped  chloroplast  with 
one  pyrenoid,  an  eye  spot,  and  two  cilia  whose  length  is  2-3  times  the 
diameter  of  the  cell.  3-10  asexual  colonies  formed  inside  the  coeno- 
bium  and  these  daughter  colonies  in  turn  frequently  containing  young 
colonies.  Asexual  reproductive  cells  becoming  much  larger  than  vege- 
tative cells  before  division  commences.  Colonies  dioecious,  with  oogonia 
and  antheridia  in  young  daughter  colonies  only.  20-60  cells  of  a 
young  colony  formng  typical  Volvox  antheridia  that  generally  contain 
64  antherozoids.  Female  colonies  with  6-10  oospheres.  Zygote  smooth 
walled. 

Vegetative  cells  5-8  /x  in  diam.  Colonies  50-350  /x  in  diam. 

Monona  (aaa). 


Order  PROTOCOCCALES. 

Vegetative  cells  immobile;  free-floating,  sessile,  or  epiphytic;  solitary 
or  in  colonies.  Colonies  amorphous  and  frequently  embedded  in  a 
gelatinous  envelope ; or  of  deflnite  shape  and  with  or  without  a gelati- 
envelope.  Colonies  capable  or  incapable  of  increasing  the  number  of 
their  cells  after  they  are  formed.  Cells  variously  shaped,  generally 
with  one  chloroplast  and  pyrenoid. 

Asexual  reproduction  by  zoospores,  fragmentation  of  the  colony,  auto- 
spores, or  autocolonies.  Resting  akinetes  known  in  some  species. 

Sexual  reproduction  by  isogamous  zoogametes  known  but  not  found 
in  a majority  of  the  genera. 


100 


WI8C0N8IN  PHYTOPLANKTON 


KEY  TO  THE  FAMILIES. 


Asexual  reproduction  by  zoospores. 

Cells  epiphytic  or  endophytic Planospobaceiab 

Cells  or  colonies  free-floating. 

Colonies  capable  of  growth  by  cell  division Palmeuaceae 

Colonies  incapable  of  growth  by  cell  division Hydeodictyaceai: 

Asexual  reproduction  by  autospores  or  division  of  cells. 

Cells  capable  of  vegetative  division. 

Solitary,  in  regular  masses,  or  in  strata Pbotoooccaceae 

In  colonies  held  together  by  remains  of  old  cell  walls . . Dictyosphaeriaceae 
Cells  incapable  of  division  except  to  form  autospores Autospoeaceak 


Family  PALMELLACEAE. 

Cells  spherical,  ovoid,  or  reniform;  rarely  solitary,  generally  united 
to  form  colonies  which  are  at  times  of  macroscopic  size.  Colonies  al- 
ways embedded  in  a gelatinous  matrix.  Colonies  capable  of  an  in- 
crease in  size  by  the  vegetative  division  of  the  constituent  cells.  Chloro- 
plasts  generally  single,  cup-to  disc-shaped  and  parietal ; or  star-shaped 
and  central ; with  or  without  pyrenoids. 

Keproduction  by  the  fragmentation  of  the  colony  or  by  zoospores. 

Sexual  reproduction  known  in  certain  genera. 


KEY  TO  THE  GENERA. 


Chloroplast  star-shaped  and  central Asterococcus 

Chloroplast  cup-  to  disc-shaped  and  parietal. 

Cells  with  pseudocilia Teteaspoea 

Cells  without  pseudocilia. 

Gelatinous  envelope  of  colony  lamellated Gloeocystis 

Gelatinous  envelope  of  colony  homogeneous. 

Cells  spherical. 

Chloroplast  of  old  cells  cup-shaped Sphaerocystis 

Chloroplast  of  old  cells  disciform Planktosphaeeia 

Cells  ovoid  to  reniform Gloeooystopsis 


GLOEOCYSTIS  Nageli  1849. 

Cells  spherical;  solitary  or  in  small  colonies  of  eight  cells  or  less. 
Each  cell  and  the  whole  colony  surrounded  by  a hyaline,  lamellated, 
gelatinous  sheath.  Chloroplast  of  young  cells  cup -shaped,  parietal,  and 
with  one  pyrenoid;  generally  diffuse  and  rich  in  starch  in  old  cells. 

Asexual  reproduction  by  a fragmentation  of  the  colony  through  the 
softening  of  the  gelatinous  envelope,  or  by  zoospores.  Akinetes  known. 


WISCONSIN  PHYTOPLANKTON 


101 


Gloeocystis  gigas  (Kiitzing)  Lagerheim.  PL  19,  Fig.  2. 

ofvers.  kgl.  Vet-Ak.  Fork.  40:  No.  3:  63.  1883;  G.  S.  West,  Brit.  Freshw. 
Algae  245;  figs.  113f-H3h.  1904. 

Cells  spherical;  solitary  or  in  families  of  2-8;  enclosed  by  a thick, 
distinctly  lamellated,  gelatinous  envelope.  Chloroplast  of  young  cells 
cup-shaped,  of  older  cells  diffuse.  (Tyehoplanktont). 

Cells  9-17  /A  in  diam. ; colonies  45-95  /jl  in  diam. 

Mendota  (rr),  Oconomowoc  (rr). 


SPHAEROCYSTIS  Chodat  1897. 

Colonies  spherical  with  the  cells  in  groups  of  4-8-16-32  and  disposed 
towards  the  periphery  of  a hyaline,  homogeneous,  gelatinous  envelope 
and  with  the  envelope  surrounding  each  group  of  cells  distinct  or  con- 
fluent with  the  colonial  envelope.  Colonies  sometimes  forming  palmella 
stages  where  the  cells  are  irregularly  disposed.  Cells  spherical ; chloro- 
plast cup-shaped  or  filling  the  entire  cell,  with  one  pyrenoid. 

Reproduction  by  the  liberation  of  a group  of  cells  through  the  soften- 
ing of  the  colonial  envelope.  Zoospores  of  two  sizes  have  been  observed, 

Sphaerocystis  Schroeteri  Chodat.  PI.  19,  Figs.  S-4. 

Bull.  Herb.  Boiss.  5:  119,  ph  9,  figs.  1-12.  1897;  G.  <S.  West,  Jour.  Linn.  Soc. 
Bot.  39:  76,  figs.  9a-9f.  1909. 

Characters  the  same  as  those  of  the  genus.  (Euplanktont). 

Diam.  cells  6-22  ^ ; diam.  colonies  50-500  fi. 

Balsam  (rr),  Bear  (2)  (ss),  Bear  Trap  (sss),  Beasley  (rr).  Big  (sss).  Big 
Butternut  (rr),  Birch  (1)  (rr),  Birch  (2)  (ss),  Birch  Island  (rr),  Boulder 
(ss),  Browns  (rr).  Camp  (rr),  Carson  (rr).  Catfish  (rr).  Center  (rr),  Chetac 
(ss),  Chetek  (cc).  Clam  (rrr).  Clear  Crooked  (s).  Crab  (r).  Cranberry  (rr). 
Deer  (rr).  Devils  (1)  (sss).  Eagle  (rr).  East  (rr),  Elizabeth  (sss).  Found  (r) 
Fowler  (rr),  Green  (1)  (rr).  Half  Moon  (rr),  Hillman  (rr).  Hooker  (rr), 
Kimball  (rr).  Kitten  (rr).  Lac  Court  Oreilles  (rr).  Lac  du  Flambeau  (r). 
Lac  la  Belle  (ss).  Little  Bass  (1)  (ss).  Little  Butternut  (r).  Little  Doctor 
(rr).  Little  Wood  (rr).  Long  (1)  (ss).  Long  (2)  (rr),  Long  (3)  (rrr).  Love- 
less (rr).  Lower  Nashotah  (rr).  Lower  Nemahbin  (cc).  Lower  Turtle  (r), 
Mary  (ss),  Mendota  (r),  Meta  (ccc).  Mill  (sss),  Monona  (r).  Mud  (1)  (rr), 
Mudhen  (sss),  Nicaboyne  (r).  No  Mans  (rr).  North  Turtle  (rr).  North  Twin 
(rr).  Number  One  (cc),  Oconomowoc  (ss),  Okauchee  (ss).  Old  Taylors  (rr). 
Pike  (rr).  Pine  (2)  (rr).  Pine  Tree  (rr),  Pokegama  (1)  (ss),  Pokegama  (3) 
(sss).  Poplar  (ss).  Prairie  (ss).  Rainbow  (rr),  Rice  (1)  (ss).  Rock  (r). 
Round  (1)  (rrr).  Round  (2)  (rr),  Rudolph  (rr).  Sand  (3)  (rr).  Sand  (4) 
(rrr).  Shell  (ccc).  Silver  (2)  (r).  South  Turtle  (r).  Tamarack  (rr).  Upper 
Nemahbin  (rr).  Upper  Turtle  (rr),  Waubesa  (rr),  Winnebago  (r). 


102 


WISCONSIN  PHYTOPLANKTON 


Lemmermann  follows  Wille  in  placing  the  alga  as  a synonym  of 
Braun’s  old  genus  Gloeococcus  but  I prefer  to  follow  G.  S.  West’s 
practice  and  consider  the  two  genera  distinct.  The  ordinary  vegetative 
condition  is  easily  recognized  but  the  rather  rare  palmella  stage  may  be 
mistaken  for  one  of  the  limnetic  Tetraspora  species. 

TETRASPOBA  Link  1809. 

Colonies  macroscopic  or  microscopic ; attached  or  free-floating ; gelat- 
inous ; spherical,  cylindrical,  expanded,  or  variously  lobed.  Cells  spher- 
ical, generally  in  groups  of  four  towards  the  periphery  of  the  homo- 
geneous, hyaline,  gelatinous  colonial  envelope.  Sometimes  irregularly 
distributed  within  the  gelatinous  colonial  envelope.  Chloroplast  cup- 
shaped, parietal ; sometimes  diffuse ; with  one  pyrenoid.  Each  cell  with 
two  or  four  long,  hyaline,  gelatinous  bristles  (pseudocilia). 

Asexual  reproduction  by  the  direct  metamorphosis  of  vegetative  cells 
into  biciliate  zoospores. 

Sexual  reproduction  by  a division  of  vegetative  cells  to  form  4-8 
bilciliate  zoogametes  that  fuse  in  pairs. 

Tetraspora  lacustris  Lemmermann.  PI.  19,  Figs.  5-6. 

Bot.  Cent.  76:  152.  1898;  Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  7:  118,  pi.  1, 
fig.  13.  189’9. 

Colonies  microscopic;  spherical,  elongate,  or  irregular  in  shape;  al- 
ways free-floating.  Cells  spherical,  generally  in  groups  of  four  and 
with  pseudocilia  6-8  times  as  long  as  the  diameter  of  the  cell.  Chloro- 
plast single,  cup-shaped,  and  parietal ; with  or  without  pyrenoids.  (Eu- 
planktont). 

Diam.  cells  7-10  /x;  diam.  colonies  up  to  300  /x. 

Crawling  Stone  (sss),  Fence  (rrr),  Long  (3)  (sss),  Mud  (2)  (sss),  Pike 
(rrr). 

Small  colonies  frequently  resemble  palmella  stages  of  Sphaerooystis 
Schroeteri  but  Tetraspora  may  be  recognized  by  the  pseudocilia.  In 
case  of  doubt  it  is  always  advisable  to  stain  with  safranin  to  bring  out 
the  pseudocilia. 


GLOEOCYSTOPSIS  G.  M.  Smith  1916. 

Cells  elongate-cylindrical,  with  rounded  ends  and  more  or  less  curved. 
Cells  aggregated  in  fours  or  eights  within  a homogeneous  gelatinous 
sheath.  Colonies  spherical  to  ovoid  and  composed  of  an  indefinite  num- 
ber of  these  aggregates.  Colony  not  enclosed  by  a gelatinous  sheath. 


WISCONSIN  PHYTOPLANKTON 


103 


Chloroplast  of  young  cells  single,  laminate,  parietal,  with  one  pyrenoid ; 
diffuse  in  old  cells. 

Reproduction,  aside  from  vegetative  cell  division,  unknown. 

Gloeocystopsis  limneticus  G.  M.  Smith.  PI.  20,  Figs.  1-2. 

Bull.  Torr.  Bot.  Cl.  43:  475,  pi.  24,  fig-  12.  1916. 

Cells  4-6  fji  broad,  10-15  fx  long.  Cell  aggregates  25-30  fi  in  diam. ; 
colonies  up  to  125  /a  in  diam.  (Euplanktont). 

Bear  Trap  (rr),  Beaverdam  (rrr).  Catfish  (rr),  Harris  (rrr).  Little  Bass 
(2)  (rrr). 

A species  that  combines  the  general  external  morphological  character- 
istics of  Gloeocystis  and  the  cell  shape  of  N ephrocytium. 

PLANKTOSPHAERIA  G.  M.  Smith  1918. 

Cells  spherical,  embedded  in  a copious,  homogeneous,  hyaline,  gelat- 
inous envelope.  At  first  solitary,  later  irregularly  distributed  within 
tiie  gelatinous  envelope.  Mature  cells  with  several  parietal,  polygonal, 
flattened  chloroplasts  each  of  which  contains  a single  pyrenoid. 

Reproduction  by  liberation  of  daughter  colonies  through  the  breaking 
down  of  the  gelatinous  colonial  envelope. 

PLANKTOSPHAERIA  GELATINOSA  G.  M.  Smith.  PI.  20,  FigS.  3-6. 
Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  627,  pi.  10,  figs.  8-11.  1918. 

Specific  characters  as  described  above.  (Euplanktont). 

Diam.  cells  4.5-25  fx ; colonies  up  to  150  fx  in  diam. 

Browns  (rr),  Mendota  (r). 

The  general  appearance  of  the  colony  suggests  SpJiaerocystis 
Schroeteri  but  P.  gelatinosa  differs  in  the  numerous  parietal  chloroplasts 
of  each  cell. 


ASTEROCOCCUS  Scherffel  1908. 

Cells  spherical  or  sub-spherical,  solitary  or  in  colonies,  with  a wide, 
homogeneous  or  lamellated,  gelatinous  envelope.  Chloroplast  single, 
central,  star-shaped,  the  astral  radiations  ending  in  a disc  at  the  cell 
wall.  Pyrenoid  single,  at  the  center  of  the  chloroplast.  Certain  species 
with  two  peripheral  vacuoles  and  an  eyespot. 

Asexual  reproduction  by  vegetative  cell  division  and  biciliate  sub- 
spherical  zoospores. 

Sexual  reproduction  unknown. 


104 


WISCONSIN  PHYTOPLANKTON 


Asterococcus  limneticus  G.  M.  Smith.  PI.  20,  Figs.  7-10. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  627,  vl.  10,  figs.  3-6.  1918. 

Colonies  spherical,  rarely  ovoid,  of  4-8-16  spherical  cells  widely 
separated  from  one  another  and  lying  within  a hyaline,  homogeneous, 
gelatinous  matrix.  Chloroplast  single,  star-shaped,  with  4 or  8 (rarely 
16)  rays  coming  from  a central  mass  and  ending  in  a disc  at  the  cell 
wall.  Pyrenoid  single,  at  the  center  of  the  chloroplast.  (Euplanktont). 

Diam.  cells  7.5-35  /a;  colonies  up  to  125  /a  in  diam. 

Chain  (r),  Clam  (sss).  Crooked  (rrr).  Deer  (rrr),  Des  Moines  (rr).  Dummy 
(ss).  Fish  (sss).  Half  Moon  (rr),  Hillman  (rrr).  Horseshoe  (1)  (ss),  Horse- 
shoe (2)  (rr),  Howey  (rr).  Lac  Court  Oreilles  (ss).  Lake  of  the  Woods  (rr), 
Long  (1)  (r),  Nancy  (r).  North  Twin  (rrr),  Owen  (cc).  Reserve  (r),  Rooney 
(rr).  Sand  (1)  (r).  Sand  (3)  (r),  Shell  (cc),  Whitefish  (sss).  Wild  Goose 
(rrr). 

The  shape  and  cellular  arrangement  in  colonies  of  this  species  is 
quite  similar  to  that  of  Sphaerocystis,  but  a sharp  distinction  exists  in 
its  star-shaped  chloroplast,  a type  of  chloroplast  that  is  very  uncommon. 
The  alga  is  widely  distributed  in  the  lakes  of  northwestern  Wisconsin. 

Family  DICTYOSPHAERIACEAE. 

Cells  in  spherical  or  ovoid  colonies,  the  number  in  young  colonies  a 
multiple  of  two,  in  older  colonies  indefinite.  Colonies  with  or  without 
a gelatinous  envelope.  Cells  held  together  in  fours  or  eights  by  the 
persistence  of  the  old  mother  cell  wall  in  repeatedly  branching  four- 
armed thongs  or  irregular  threads.  Chloroplast  single;  cup-shaped, 
or  filling  the  entire  cell ; with  one  pyrenoid. 

Keproduction  by  the  division  of  cells  into  autospores  which  remain 
attached  to  mother  colony  until  accidentally  broken  away. 

KEY  TO  THE  GENERA. 


Colony  enclosed  in  a gelatinous  sheath Dictyosphaebium 

Colony  not  enclosed  in  a gelatinous  sheath. 

Cells  spherical Westella 

Cells  ovoid  to  reniform Dimobphococcus 


DICTYOSPHAERIUM  Nageli  1849. 

Cells  spherical,  ovoid,  or  reniform,  connected  with  one  another  by 
cruciately  or  dichotomously  branching  threads.  Colony  enclosed  by  a 
hyaline,  homogeneous,  gelatinous  envelope  that  is  spherical  or  ovoid  in 
shape.  Chloroplast  single,  parietal,  cup-shaped,  with  one  pyrenoid. 


WISCONSIN  PHYTOPLANKTON 


105 


Eeproduction  by  tbe  division  of  the  cell  into  2 or  4 daughter  cells 
which  remain  connected  to  the  colony  by  the  old  mother  cell  wall  that 
divides  into  2 or  4 parts  to  form  the  branching  thread  system  connect- 
ing the  cells.  Zoospores  reported  but  their  existence  is  very  doubtful. 
Resting  akinetes  known. 


KEY  TO  THE  SPECIES. 

Mature  cells  ovoid D.  Ehrenbergianum 

Mature  cells  spherical D.  Ptjlchellxjm 

Dictyosphaerium  Ehrenbergianum  Nageli.  PI.  20,  Figs.  11-12. 
Gatt.  einz.  Algen,  73,  pJ.  2,  figs.  Ea-ES  1849. 

Colonies  spherical  to  ovoid,  rarely  containing  more  than  30  cells. 
Cells  ovoid  to  ellipsoid  when  mature.  Chloroplasts  1-2,  parietal,  lami- 
nate, generally  with  a single  pyrenoid.  (Facultative  Planktont). 

Cells  4-7  jw.  broad ; 6-10  ja  long. 

Clear  (rr),  Kegonsa  (rrr>.  Mendota  (rr). 

Dictyosphaerium  pulchellum  Wood.  PI.  20,  Fig.  13;  PI.  21,  Fig.  1. 
Smithsonian  cont.  to  knowl.  19,  No.  241:  84,  pZ.  10,  fig.  4.  1872. 

Colonies  spherical  to  broadly  ovoid,  of  4-8-16-32  or  many  cells  lying 
near  the  periphery  of  the  hyaline,  homogeneous,  gelatinous  envelope. 
Cells  spherical  when  mature,  spherical  to  ovoid  when  young ; generally 
in  fours  at  the  ends  of  a repeatedly  branching  system  of  threads.  Chloro- 
plast  single,  parietal,  cup-shaped,  with  one  pyrenoid.  (Facultative 
pJanktont). 

Diam.  cells  3-10  /t. 

Amicoy  (ss).  Balsam  (rrr).  Bear  (1)  (ss).  Bear  (2)  (r),  Bettine  (s).  Big 
Butternut  (r),  Birch  (1)  (r),  Birch  (2)  (rrr),  Blake  (ss).  Bone  (r),  Boulder 
(rrr).  Canteen  (rr),  Carson  (sss).  Catfish  (r),  Catherine  (rrr).  Center  (r). 
Chain  (rr),  Chetac  (ss),  Chetek  (ss).  Crab  (s).  Cranberry  (rr).  Crawling 
Stone  (rrr).  Deer  (rr),  Diamond  (rr).  Duck  (cc).  Dummy  (sss).  Eagle  (rr), 
Elizabeth  (rrr),  Pishtrap  (rr).  Granite  (ss).  Grassy  (rr).  Grindstone  (rr). 
Half  Moon  (rr).  High  (rr),  Hillman  (ss).  Horse  (rr).  Horseshoe  (1)  (rrr). 
Horseshoe  (2)  (ss),  Howey  (rr),  Jag  (rr),  Kawaguesaga  (rr),  Kegonsa  (r). 
Kitten  (rrr).  Lac  Court  Oreilles  (ss).  Lac  du  Flambeau  (rr),  Lindy  (rr). 
Little  Bass  (1)  (rr),  Little  Bass  (2)  (rr).  Little  Butternut  (rr).  Little  Crooked 
(rrr).  Little  Bice  (2)  (sss).  Little  Wood  (sss).  Long  (1)  (rrr).  Long  (3) 
(rrr).  Loon  (r).  Loveless  (rr).  Lower  Turtle  (r).  Lynx  (rrr),  Mendota  (ss), 
Mercer  (rrr),  Middle  McKenzie  (rrr),  Monona  (ss).  Mud  (2)  (rr),  Mudhen 
(rr),  Nagawicka  (rrr),  Nancy  (r),  Nicaboyne  (rr).  North  Turtle  (r),  Ocono- 
mowoc  (r),  Okauchee  (rr).  Old  Taylors  (rr),  Owen  (rrr).  Palmer  (rr),  Pe- 
waukee  (rr).  Pine  Tree  (sss),  Pokegama  (1)  (r),  Pokegama  (3)  (c).  Poor 


106 


WISCONSIN  PHYTOPLANKTON 


Farm  (rrr),  Prairie  (c),  Reserve  (rr),  Rice  (ss),  Rock  (rr),  Rooney  (rr), 
Rose  (sss),  Rozen  (rr),  St.  Croix  (rrr),  Sand  (3)  (rrr).  Shell  (cc),  Sishe- 
bogema  (rr),  (South  Turtle  (rr).  Spirit  (r).  Tamarack  (sss).  Tenderfoot  (rr). 
Tied  Canoe  (rrr),  Travis  (rr).  Upper  Nashotah  (sss).  Upper  Nemahbin  (rr). 
Vermilion  (r),  Wapagossett  (rrr),  Waubesa  (ss).  White  Ash  (sss),  Whitefish 
(rr).  White  Sand  (rr),  Wild  Goose  (s),  Winnebago  (sss). 

DIMORPHOCOCCUS  A.  Braun  1855. 

Ceils  in  groups  of  four  and  held  in  an  irregular  free-floating  colony 
by  the  branching  remains  of  the  old  mother  cell  wall.  Colony  not  en- 
closed by  a gelatinous  envelope.  Each  aggregate  of  four  cells  lying  in 
one  plane  with  two  cells  ovoid  to  cylindrical  with  rounded  ends,  and  two 
cells  reniform  to  cardioid.  Chloroplast  of  young  cells  single,  parietal, 
laminate,  with  one  pyrenoid;  chloroplast  of  old  cells  occupying  the 
entire  cell. 

Reproduction  by  the  division  of  any  cell  into  four  daughter  cells 
which  remain  attached  to  the  colony  by  the  threadlike  remains  of  old 
cell  wall  until  accidentally  broken  away. 

Dimorphococcus  lunatus  a.  Braun.  PI.  21,  Fig.  5. 

Alg.  Unicell.  44.  1855;  Rabenhorst,  FI.  Bur.  Algarum  3:  3G,  figs,  a-c  (p.  6). 

1868;  G.  S.  West,  Brit.  Freshw.  Algae  221,  figs.  93a-93b.  1904. 

Cells  of  each  group  of  four  alternately  arranged  (in  vertical  view) 
the  central  cells  cylindrical  with  rounded  ends,  the  terminal  cells  reni- 
form to  cardioid.  (Facultative  planktont). 

Cells  4-15  fi  broad,  9-25  /x  long.  Colonies  up  to  150  /x  in  diam. 

Bear  (2)  (rr).  Bear  (3)  (rr),  Beaver  dam  (rrr),  Blue  Gill  (rrr),  Catfish 
(rr),  Des  Moines  (rrr).  Devils  (2)  (rr).  Horseshoe  (1)  (rr),  Horseshoe  (2) 
(rrr),  Kegonsa  (rrr),  Lindy  (rr),  Minocqua  (rrr).  Mud  (1)  (rr),  Pike  (rr), 
Pine  (1)  (rr).  Pine  Tree  (rrr),  St.  Croix  (rrr).  Shell  (rrr). 


WESTELLA  de  Wildeman  1897. 

Cells  small,  spherical  to  sub-spherical,  grouped  in  fours  (rarely 
eights)  in  irregular,  free-floating  colonies  containing  30-100  cells;  the 
colony  being  held  together  by  the  non-gelatinizing  remains  of  the  old 
mother  cell  walls.  Colonies  without  a gelatinous  envelope.  Chloro- 
plast cup-shaped  and  parietal,  or  entirely  filling  the  cell,  with  or  with- 
out a pyrenoid. 

Reproduction  by  the  division  of  any  cell  to  form  4^S  autospores  that 
remain  connected  with  the  mother  colony  until  accidentally  broken 
away. 


WISCONSIN  PHYTOPLANKTON 


107 


KEY  TO  THE  SPECIES. 


Groups  with  cells  quadrate  or  pyramidate W.  Botryoides 

Groups  with  cells  in  a linear  series W.  Linearis 


Westella  botryoides  (W.  West)  de  Wildeman.  PL  21,  Fig.  4. 
Bull.  Herb.  Boiss.  5:  532.  1897. 

Tetracoccus  'botryoides  W.  West,  Jour.  Roy.  Micr.  Soc.  1892:  735,  pi.  10, 
ags.  43-48.  1892. 

Colonies  irregularly  shaped,  without  a gelatinous  envelope,  generally 
containing  40-80  cells.  Cells  spherical,  pyramidately  or  quadrately 
arranged  in  groups  of  four  (rarely  eight).  Chloroplast  single,  cup- 
shaped or  entirely  filling  the  cell;  with  or  without  a pyrenoid.  (Facul- 
tative Planktont). 

Diam.  cells  3-9  /a. 

Blake  (rrr),  Fishtrap  (rr),  Hillman  (rrr),  Horse  (rrr),  Horseshoe  (1)  (rr), 
Jag  (r),  Little  Bass  (2)  (rr),  Little  Butternut  (rrr).  Little  Crooked  (rr), 
Mendota  (rrr).  Mill  (rrr),  Nancy  (rr).  Pine  Tree  (rr).  Round  (3)  (rr), 
Sishebogema  (rr). 

var.  MAJOR  G.  M.  Smith. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  628.  1918. 

Cells  larger  than  the  typical  form,  otherwise  the  same. 

Diam.  cells  8-13  /a. 

Whitefish  (rr). 


Westella  linearis  sp.  nov.  PI.  21,  Figs.  2-3. 

Colonies  of  irregular  shape,  rarely  containing  more  than  40  cells. 
Cells  spherical,  always  in  groups  of  four  and  arranged  in  a linear 
series.  Kemains  of  old  mother  cell  walls  that  hold  the  colony  together 
very  inconspicuous.  Colony  without  a gelatinous  envelope.  Chloro- 
plast single,  parietal,  without  a pyrenoid.  (Euplanktont  ?). 

Diam.  cells  3-6  /a. 

Pine  Tree  (rr). 

In  the  arrangement  of  the  cells  this  species  is  quite  unlike  the  other 
members  of  the  genus  but  since  the  cells  are  in  groups  of  four  that  are 
held  together  by  the  remains  of  old  mother  cell  walls  it  seems  better 
to  place  it  in  this  genus  than  in  Crucigenia. 


108 


WISCONSIN  PHYTOPLANKTON 


Family  PROTOCOCCACEAE. 

Cells  solitary  and  spherical;  or  in  colonies  containing  an  indefinite 
number  of  cells  that  are  spherical  and  mutually  compressed  or  in  very 
short  irregular  filaments.  Cell  wall  delicate  to  heavy,  smooth  or  vari- 
ously sculptured.  Chloroplast  single,  parietal  and  disciform,  with  or 
without  pyrenoids.  Cells  capable  of  vegetative  division. 

Reproduction,  aside  from  vegetative  division  of  cells,  by  zoospores  or 
aplanospores. 


KEY  TO  THE  GENERA. 


Cell  wall  thin,  smooth Chlorella 

Cell  wall  thick,  sculptured Teochiscia 


CHLORELLA  Beyerinck  1890. 

Cells  small,  spherical ; solitary  or  in  small  colonies  of  indefinite  shape. 
Chloroplast  disciform  to  cup-shaped,  with  or  without  a pyrenoid. 

Reproduction  by  the  division  of  cell  contents  into  2-4-8  daughter 
cells.  Resting  akinetes  known. 

Chlorella  vulgaris  Beyerinck.  PI.  22,  Fig.  1. 

Bot.  Ztg.  48:  758,  pi.  7,  figs.  2a-2b.  18'90. 

Cells  spherical,  generally  solitary.  Chloroplast  parietal,  cup-shaped, 
with  or  without  a pyrenoid.  Cell  wall  smooth  and  delicate.  (Faculta- 
tive Planktont). 

Diam.  cells  5-10  /a. 

Mendota  (rr). 

C.  vulgaris  is  a minute  alga  and  one  that  is  easily  overlooked.  The 
record  of  its  occurrence  in  Lake  Mendota  is  based  upon  its  isolation  by 
pure  culture  methods  from  a plankton  catch.  It  is  very  probable  that 
it  is  present  in  other  lakes  but  has  been  overlooked. 

TROCHISCIA.  Kiitznig  1845. 

Cells  spherical  to  sub-spherical,  solitary  or  in  small  clumps.  Cell 
wall  fairly  heavy,  areolate  or  ornamented  vdth  spines,  denticulations, 
ridges,  or  other  projections.  Cells  generally  containing  several  parietal 
disciform  chloroplasts  each  with  a pyrenoid. 

Reproduction  by  vegetative  cell  division  or  the  formation  of  -4-16 
aplanospores  that  are  liberated  by  the  dissolution  of  the  old  mother 
cell  wall. 


WISCONSIN  PHYTOPLANKTON 


109 


Trochiscia  reticularis  (Reinscli)  Hansgirg.  PI.  22,  Fig.  2. 
Hedwigia  27:  129.  1888. 

Acanthococcyiis  reticularis  Reinsch,  Ber.  d.  D.  bot.  Ges,  4:  242,  pZ.  12,  figs. 
24a-24b.  1886. 

Cells  generally  solitary,  spherical.  Cell  wall  fairly  thick  and  covered 
with  linear  ridges  that  intersect  to  form  50-70  polygons  on  the  surface 
of  the  cell.  (Tychoplanktont). 

Diam.  cells  24-32  /x. 

Wildcat  (rrr). 


Family  AUTOSFOEACEAE. 

Cells  solitary  or  in  colonies  that  are  generally  of  a definite  shape  and 
without  a gelatinous  envelope.  Cells  variously  shaped;  with  a single 
chloroplast  and  pyrenoid  as  a rule.  Cells  incapable  of  vegetative  divi- 
sion to  form  two  similar  daughter  cells. 

Reproduction  by  division  of  cell  contents  into  2-4r-8-l 6-32-64  cells 
which  assume  the  shape  of  the  mother  cell  before  their  liberation  (auto- 
spores). In  the  colonial  species  the  autospores  from  any  one  cell  are 
organized  to  form  the  new  colony  (autocolony)  before  their  liberation. 
Motile  asexual  reproductive  bodies  or  sexual  reproduction  unknown. 


KEY  TO  THE  SUBFAMILIES. 


Cells  solitary. 

Cells  angular Tetraedreae 

Cells  not  angular. 

Ornamented  with  long  spines  or  setae Micractinieae  (p.  p.) 

Not  ornamented  with  spines  or  setae. 

Length  of  cells  several  times  the  diameter Selenastreae  (p.  p.) 


Length  of  cells  not  more  than  twice  the  diameter Oocysteae  (p.  p.) 

Cells  in  colonies. 

Ornamented  with  long  setae  or  spines. 

Coenohe  capable  of  growth  in  three  directions Micractinieae  (p.  p.) 

Coenobe  a flat  plate Crucigenieae  (p.  p.) 

Not  ornamented  with  setae  or  spines. 

Number  of  cells  in  coenobe  always  a multiple  of  two. 

Coenobe  flat Crucigenieae  (p.  p ) 

Coenobe  spherical  or  cells  radiating  from  a common 

center  > Coelastreak 

Number  of  cells  not  a multiple  of  two  in  every  case. 

Cells  elongate,  straight  or  curved Selenastreae  (p.  p.) 

Cells  spherical,  ovoid,  or  reniform Oocysteae  (p.  p.) 


110 


WISCONSIN  PHYTOPLANKTON 


Subfamily  OOCYSTEAE, 

Cells  spherical,  ovoid,  or  renif orm ; solitary  or  in  temporary  colonies. 
Daughter  cells  retained  within  old  mother  cell  wall  for  some  time  after 
their  formation.  Walls  generally  thick  and  cells  with  one  to  many 
chloroplasts. 


KEY  TO  THE  GENERA. 

Cells  within  old  mother  cell  wall  separated  by  a dark  gelatinous 

mass Gloeotaenium 

Cells  within  old  mother  ceil  wall  not  separated  by  a dark  gelat- 
inous mass. 

Cells  ovoid  to  elliptic,  never  curved Oocystis 

Cells  ovoid  to  reniform,  frequently  curved Nepheooytium 

OOCYSTIS  Nageli  1845. 

Cells  ovoid,  ellipsoid,  or  cylindrical  with  rounded  to  somewhat  pointed 
ends,  generally  symmetrical  but  never  curved.  Cell  wall  smooth,  with- 
out spines,  frequently  with  nodular  thickenings  at  the  poles.  Chloro- 
plasts one  to  many;  parietal,  disciform,  stellate,  or  reticulate;  with  or 
without  pyrenoids.  Cells  solitary  or  in  temporary  colonies  of  2-4-8-16 
or  more  enclosed  by  the  partially  gelatinized  and  greatly  swollen  old 
mother  cell  wall. 

Reproduction  by  a formation  of  2-4^8-16  autospores  that  remain 
within  the  old  cell  wall  for  some  time.  Three  to  four  cell  generations 
sometimes  enclosed  by  the  same  wall.  Tetraedron-YAiQ  resting  spores 
with  granulate  walls  have  been  observed. 

The  genus  differs  from  others  in  the  expanded  cell  wall  that  encloses 
the  cells  in  temporary  colonies.  Printz  (Nyt.  Mag.  f.  Naturvidensk. 
1913,  p.  165)  has  recently  monographed  the  genus  and  cleared  up  many 
points  by  collecting  the  published  descriptions  of  species;  but  there  is 
great  need  of  a series  of  cultural  studies  to  determine  the  range  of 
variation  within  the  so-called  “species”  that  are  recognized  at  the 
present  time. 


KEY  TO  THE  SPECIES. 


Cbloroplast  stellate O.  Natans 

Cbloroplast  disciform  to  laminate. 

Cells  with  polar  nodules. 

Sides  of  cells  concave O.  Pandubifobmis 

Sides  of  cells  convex. 

4 or  more  chloroplasts  in  each  cell. 

Cells  with  40-60  chloroplasts O.  Ebemosphaebia 


WISCONSIN  PHYTOPLANKTON 


111 


Cells  with  6-25  chloroplasts. 

Polar  nodules  conspicuous,  12-25  chloroplasts O.  Solitaria 

Polar  nodules  not  prominent,  4-10  chloroplasts O.  Crassa 

1-2  (rarely  4)  chloroplasts  in  each  cell. 

Cells  elliptic,  length  ll^  times  breadth O.  Lacustris 

Cells  oblong-cylindrical,  length  2-3  times  breadth O.  Submaeina 

Cells  without  polar  nodules. 

Poles  of  cells  rounded. 

Length  of  cells  less  than  12  /x O.  Pusilla 

Length  of  cells  more  than  12  /x. 

1-4  chloroplasts  in  each  cell O.  Bobgei 

8-10  chloroplasts  in  each  cell O.  Elliptica 

Poles  of  cells  pointed. 

Old  cell  wall  enclosing  colonies  rounded 0.  Parva 


Old  cell  wall  enclosing  colony  sharply  pointed.. 0.  Gloeocystiformis 

OocYSTis  PusiLLA  Hansgirg.  PL  22,  Fig.  3. 

Sitzbr.  d.  k.  bohm.  Ges.  d.  Wiss.  in  Prag,  Jahrgang  1890:  9.  1890;  Printz,  Nyt. 
Mag.  f.  Naturvidensk.  51:  181,  pi.  4,  figs.  31-32.  1913. 

Cells  cylindrical,  poles  rounded  and  without  nodules.  Chloroplasts 
2-3,  parietal,  laminate,  without  pyrenoids.  Temporary  colonies  con- 
taining 2-^L-8  cells.  (Tychoplanktont). 

Diam.  cells  4. 5-6. 5 /x ; length  8-12  fx. 

Tied  Canoe  (rr). 

OocYSTis  Borgei  Snow.  PL  22,  Fig.  4. 

Bull.  U.  S.  Fish  Comm.  22:  379,  pi.  2,  figs.  VIP-VIP.  1903. 

Cells  broadly  elliptic,  length  1%  times  the  breadth;  poles  rounded 
but  without  nodules.  Chloroplasts  1^,  parietal,  laminate,  each  con- 
taining a single  pyrenoid.  Cells  solitary  or  in  families  of  2-4-8  within 
an  old  mother  cell  wall.  (Euplanktont). 

Cells  9-13  broad,  9-17  fi  long. 

Big  (rr),  Birch  (1)  (sss).  Camp  (r),  Catfish  (r).  Devils  (1)  (rr).  Duck 
(r).  Found  (rr).  Green  (2)  (rr),  Kawaguesaga  (rr).  Kitten  (rrr).  Long  (2) 
(rr),  Mendota  (r).  North  Turtle  (r),  Pardee  (rr).  Rock  (r),  Winnebago  (rr). 

OocYSTis  ELLIPTICA  W.  West.  PL  22,  Pig.  5. 

Jour.  Roy.  Micr.  Soc.  1892:  736,  pi.  10,  fig.  56.  1892. 

Cells  oblong-elliptic,  with  poles  rounded  and  without  nodules.  Chlor- 
oplasts 10-20,  disciform,  parietal,  without  ( ?)  pyrenoids.  Cells  rarely 
solitary,  generally  in  families  of  4-8  within  an  old  mother  cell  wall. 
( Tychoplanktont) . 

Cells  11-12.5  /X  broad,  20-25  /x  long. 

Amicoy  (rr). 


112 


WISCONSIN  PHYTOPLANKTON 


OocYSTis  PARVA  W.  & G.  S.  West.  PL  22,  Fig.  6. 

Jour,  of  Bot.  36:  335.  1898;  G.  S.  West,  ibid.  37:  223,  pi.  394,  iigs.  14-17.  1899. 

Cells  broadly  fusiform  to  elliptic,  ends  pointed  but  without  polar 
nodules.  Each  cell  with  1-3  parietal,  laminate  to  disciform  chloro^ 
plasts,  with  or  without  pyrenoids.  Cells  solitary  or  in  families  of  2-^r-8. 
(Facultative  Planktont). 

Cells  4-7  ft  broad ; 6-12  ft  long. 

Beaver  (1)  (rr),  Bettine  (rr).  Clear  Crooked  (rr),  Cochrane  (rrr).  Crab 
(rrr).  Deer  (rr),  George  (rr).  Half  Moon  (rr).  Hooker  (rr).  Little  Bass  (2) 
(rr).  Lynx  (rr),  Mendota  (rr),  Muskallonge  (rr).  Palmer  (rr),  Pine  (1)  (rr), 
Rudolph  (rr).  Sand  (1)  (rrr).  Stone  (rr),  Wolf  (rr). 

OocYSTis  GLOEOCYSTiFORMis  Borge.  PL  22,  Fig.  7. 

Botaniska  Studier  till.  F.  R.  Kjellman  23,  pi.  1,  figs,  la- lb.  1906. 

Cells  narrowly  elliptic  with  ends  pointed.  Chloroplast  single,  pari- 
etal, without  a pyrenoid.  Cells  in  families  of  2-4  within  the  old  cell 
wall,  several  cell  generations  frequently  forming  a single  colony.  Wall 
enclosing  colony  with  pointed  ends  but  no  polar  nodules.  (Tychoplank- 
tont). 

Breadth  of  cell  3-5.5  ft ; length  8-15  ft. 

Lac  Court  Oreilles  (sss). 

The  old  mother  cell  wall  does  not  gelatinize  as  readily  in  this  species 
as  in  others  so  that  several  cell  generations  are  generally  found  in  the 
same  colony.  The  species  is  best  recognized,  however,  by  the  sharply 
pointed  ends  of  the  colony  waU. 

OocYSTis  LAcuSTRis  Chodat.  PL  22,  Figs.  8-9. 

Bull.  Herb.  Boiss.  5:  119,  pi.  10,  figs.  1-7.  1897. 

Cells  elliptic  to  broadly  fusiform,  somewhat  pointed  and  with  a 
nodule  at  the  poles.  Chloroplasts  1-3,  laminate,  parietal,  with  or  with- 
out pyrenoids.  Margins  of  chloroplasts  sometimes  irregular.  Cells 
rarely  solitary,  generally  in  families  of  2-4-8  within  the  old  mother 
cell  wall.  (Euplanktont). 

Cells  8-22  fi  broad,  14-32  ft  long. 

Big  Butternut  (rr),  Bone  (rr).  Center  (r).  Chain  (rr),  Chetek  (r).  Devils 
(2)  (ss).  Dummy  (rr),  Fowler  (rr),  Hillman  (rr),  Little  Bass  (2)  (rr). 
Little  Butternut  (rrr).  Long  (2)  (rrr),  Long  (3)  (rrr),  Mary  (r),  Mercer 
(rr),  Palmer  (rr),  Pokegama  (3)  (rr).  Prairie  (rr),  Reserve  (rr).  Sand  (4) 
(rr),  Sishebogema  (rrr),  Upper  Nashotah  (rrr),  Upper  Turtle  (sss).  White 
Sand  (rr). 


WISCONSIN  PHYTOPLANKTON 


113 


OocYSTis  SUBMARINA  Lagerheim.  PI.  22,  Fig.  10. 

Bot.  Not.  1886  : 45,  iig.  1.  1886. 

Cells  oblong-cylindrical,  2-3  times  as  long  as  broad,  somewhat  pointed 
and  with  a nodule  at  each  pole.  Chloroplasts  1-2,  laminate,  parietal, 
usually  with  a pyrenoid.  Cells  rarely  solitary,  generally  in  families 
of  2-d^8-16  within  the  old  mother  cell  wall.  (Tychoplanktont). 

Cells  3-9  IX  broad,  7-20  /x  long. 

Camp  (sss),  Upper  Nemahbin  (rr). 

OocYSTis  SOLITARIA  Wittrock.  PL  22,  Fig.  11. 

Bot.  Not.  1879:  24,  figs.  1-5.  1879. 

Cells  ovoid  to  ellipsoid,  solitary  or  in  families  of  2-4r-8.  Cell  wall 
fairly  thick  and  with  conspicuous  polar  nodules.  Chloroplasts  numer- 
ous (generally  12-25),  parietal,  disciform  to  polygonal,  with  or  with- 
out pyrenoids.  (Facultative  Planktont). 

Cells  7-20  /X  broad,  14-35  /x  long. 

Hooker  (r).  Sand  (1)  (rr). 

OocYSTis  CRASSA  Wittrock.  PL  22,  Figs.  12-13. 

Bot.  Not.  1880:  117.  1880. 

Cells  ovoid,  length  1%  times  the  breadth,  with  a nodule  at  each  pole. 
Chloroplasts  4-10  in  number,  fairly  large,  parietal,  disciform  to  angu- 
lar, generally  with  a pyrenoid.  Cells  solitary  or  in  families  of  2-4-8. 
Old  cell  wall  enclosing  the  colony  greatly  distended.  (Tychoplanktont) . 
Cells  10-20  /X  broad,  11^26  fx  long. 

St.  Croix  (rr). 

OocYSTis  EREMOSPHAERiA  G.  M.  Smith.  PL  23,  Figs.  1-2. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  630,  pi.  14,  figs.  8-9.  1918. 

Cells  ovoid,  1%  to  2 times  as  long  as  broad.  Solitary  or  in  families 
of  2-4.  Chloroplasts  numerous  (40-60),  parietal,  lenticular,  each  con- 
taining a single  pyrenoid.  Cell  wall  thick,  with  a conspicuous  polar 
nodule.  (Facultative  Planktont  ?). 

Cells  23-31  fx  broad,  35-45  /x  long. 

Beaverdam  (rr).  Shell  (sss). 


8 


114 


WISCONSIN  PHYTOPLANKTON 


OocTSTis  PANDURiFORMis  YSiT.  MINOR  G.  M.  Smith.  PI.  23,  Fig.  3. 
Bull.  Torr.  Bot.  Cl.  43:  471,  pi.  24,  fig.  2.  1916. 

Cells  oblong-ovoid,  2 to  2%  times  as  long  as  broad,  sides  slightly 
concave  and  poles  with  a conspicuous  nodule.  Chloroplasts  numerous 
(15-25),  parietal,  disciform,  and  each  containing  a pyrenoid.  Cells 
solitary  or  in  families  of  2-4r-8.  (Tychoplanktont). 

Greatest  diameter  of  cells  12-15  /t,  median  diameter  11-14;  length 
30-35 

Star  (rr). 

This  is  the  only  species  of  the  genus  where  the  sides  of  the  cells  are 
concave. 

Oocystis  natans  var.  major  var.  nov.  PI.  23,  Figs.  4-5<i 

Cells  ovoid,  without  a conspicuous  polar  nodule.  Chloroplasts  4^8, 
parietal,  star-shaped  or  irregular,  each  chloroplast  with  a pyrenoid. 
More  than  two  cell  generations  rarely  found  within  the  same  mother 
cell  wall.  (Facultative  Planktont). 

Cells  16-25  broad,  31-38  /a  long.  Families  up  to  90x120  fx. 

Birch  (2)  (sss),  Chetac  (s).  Rice  (1)  (rr). 

Lemmermann  founded  the  genus  Oocystella  upon  this  stellate  nature 
of  the  chloroplast  (Zeits.  f.  Fischeri  u.  d.  Hilfsw.  11:  103.  1903)  but 
the  genus  has  not  been  recognized  and  the  single  species  is  placed  in 
Oocystis. 


NEPHROCYTIUM  Nageli  1849. 

Cells  ovoid,  reniform,  or  oblong-elliptic;  generally  in  colonies  of 
2-4—8-16  cells  within  the  partially  gelatinized  remains  of  the  old  mother 
cell  wall.  Arrangement  of  cells  in  young  colonies  spiral,  in  old  colonies 
irregular.  Chloroplast  single  and  expanded  at  first,  later  fragmenting 
and  becoming  diffuse ; pyrenoid  single. 

Reproduction  by  the  formation  of  2-4-8-16  autospores  in  each  cell. 

Nepiirocytium  Agardhianum  Nageli.  PI.  23,  Pigs.  6-7. 

Gatt.  elnz.  Algen  79,  pi.  3,  figs.  Ca-CP.  1849. 

Cells  reniform,  generally  spirally  arranged  in  young  colonies.  Chlor- 
oplast single,  parietal,  laminate,  and  with  one  pyrenoid  in  young  cells ; 
diffuse  in  old  cells.  (Tychoplanktont). 

Cells  2-12  fx  broad,  6-28  jx  long ; colonies  up  to  60  fx  long. 

Bear  (3)  (rrr).  Bear  Trap  (rrr).  Camp  (rr),  Hillman  (rr).  Little  Bass 
(rrr),  Mendota  (rr).  Mill  (rrr). 


WISCONSIN  PHYTOPLANKTON 


115 


GLOEOTAENIUM  Hansgirg  1890. 

Cells  spherical,  ovoid,  or  variously  flattened;  solitary  or  united  in 
colonies  of  2-4r-8  cells  enclosed  by  a non-expanded  mother  cell  wall  and 
separated  from  one  another  by  a dark  colored  gelatinous  mass  that  lies 
between  the  cells.  Colonies  rectangular,  with  rounded  corners  in  front 
view ; oblong  with  sharp  corners  in  side  view.  Cell  wall  thick,  distinctly 
lamellated ; old  cell  wall  enclosing  the  colony  frequently  with  folds  and 
gelatinous  discs  opposite  the  cells.  Chloroplast  entirely  Ailing  cells; 
with  or  without  a pyrenoid. 

Reproduction  by  autospores  and  aplanospores. 

Gloeotaenium  Loitlesbergerianum  Hansgirg.  PI.  23,  Pigs.  8-9. 

Sitzbr.  d,  k.  bohm.  Ges.  d.  Wiss.  in  Prag,  Jabrgang  1890:  10.  1890;  Transeau, 

Bot.  Gaz.  55:  66,  pi.  3,  figs.  1-24.  1913. 

Cells  spherical  to  ovoid,  completely  filling  the  space  inside  of  old 
mother  cell  wall.  (Tychoplanktont). 

Diam.  cells  20-30  fi;  length  2-celled  colonies  40-70  fi  breadth  22-40  fi; 
thickness  20-30  /i.  4-celled  colonies  40-70  fi  broad,  40-80  ^ long. 

Big  Butternut  (rrr). 

Sub-family  TETRAEDREAE. 

Cells  always  solitary,  without  a gelatinous  envelope,  flattened  or 
isodiametric,  triangular,  quadrangular,  or  polyangular;  angles  simple 
or  produced  into  spines  or  long  hyaline  setae. 


KEY  TO  THE  GENERA. 


Cells  simple  or  with  fairly  stout  spines  at  angles Tetraedron 

Cells  with  long  hyaline  setae  at  angles Polyedbiopsis 


TETRAEDRON  Kiitzing  1845. 

Cells  solitary,  free-floating,  flattened  or  isodiametric,  triangular, 
quadrangular,  or  polyangular.  Angles  simple  or  produced  into  simple 
or  furcate  spines.  Cell  wall  smooth  or  verrucose.  Chloroplasts  one  to 
many,  parietal,  disciform  to  angular ; or  completely  filling  the  cell ; with 
or  without  pyrenoids. 

Reproduction  by  division  of  cell  contents  into  1^8  autospores  that 
are  liberated  by  the  rupture  of  the  old  mother  cell  wall. 


116 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 

Angles  of  cells  never  produced  into  processes. 

Corners  of  cells  without  spines. 

Cells  triangular T.  Muticum 

Cells  quadrangular T.  Minimum 

Corners  of  cells  with  spines. 

All  cell  corners  in  the  same  plane. 

Cells  triangular T.  Trigonum 

Cells  with  more  than  three  angles. 

Cells  with  four  angles T.  Reguu\re  v.  Incus  (p.  p.) 

Cells  with  five  angles T.  Caudatum 

All  cell  corners  not  in  the  same  plane. 

Cells  quadrangular. 

Pyramidal  cells T.  Regulabe 

Halves  of  cells  twisted  over  one  another. 

Wall  smooth. 

Angles  delicately  tapering T.  Victorieae  var.  Major 

Angles  strongly  convex T.  Regulars  var.  Torsum  (p.  p.) 

Wall  verrucose T.  Verrucosum 

Cells  five-angled T.  Pentaedricum 

Angles  at  corners  produced  into  processes. 

Processes  always  unbranched T.  Hastatum 

Processes  always  branched. 

Cells  flattened  and  processes  in  the  same  plane. 

General  outline  of  cell  H-shaped T.  Constricum 

General  outline  of  cell  not  H-shaped. 

Processes  long,  conspicuously  branched T.  Gracilb 

Processes  short,  not  conspicuously  branched. ..  .T.  Lobulatum  (p.  p.) 
Cells  isodiametric  and  processes  not  in  the  same  plane. 

Processes  short T.  Enorme 

Processes  long. 

With  3-5  series  of  branchings T.  Lobulatum  var.  Polyfuroatum 

Never  more  than  three  series  of  branchings. 

Diameter  of  cells  always  greater  than  the  length 

of  the  processes T.  Planotonicum 

Diameter  of  cell  always  less  than  the  length  of 

the  processes T.  Limneticum 


Tetraedron  muticum  var.  punctulatum  (Reinseh)  de  Toni.  PI.  23, 

Figs.  10-13. 

Sylloge  algarum  1 : 600.  1889. 

Polyedrium  muticum  var.  punctulatum  Reinseh,  Notarisia  3:  498,  pi.  4, 
flg.  6.  1888. 

Cells  small,  triangular,  somewhat  flattened.  Sides  of  cells  convex  in 
front  view.  Corners  sharp  but  without  spines.  Cell  wall  covered  with 
small  granules.  (Tychoplanktont). 

Diam.  cells  15-20  fx;  thickness  8-10  /x. 

Beaverdam  (rr).  Deer  (rrr),  Sand  (2)  (rr). 


WISCONSIN  PHYTOPLANKTON 


117 


Tetraedron  trigonum  (Nageli)  Hansgirg.  PI.  23,  Figs.  14-16. 
Hedwigia  27:  130.  1888. 

Polyedrium  trigonum  Nageli,  Gatt.  einz.  Algen  84,  pi.  4,  ^gs.  Bla-Blb.  1849. 

Cells  medium  sized,  triangular,  flattened.  Sides  of  cells  generally 
concave,  rarely  straight.  Corners  with  a single,  stout,  straight  or  curved 
spine.  (Facultative  Planktont). 

Diam.  cells  (without  spines)  20-30  ix  \ length  spines  8-10  /x. 

Crawling  stone  (rrr).  High  (r),  Pokegama  (1)  (rr).  Rice  (1)  (rrr).  Ten- 
derfoot (rr).  Tied  Canoe  (rrr). 

var.  SETiGERUM  (Archer)  Lemmermann.  PI.  24,  Figs.  1-4. 

Arkiv.  for  Botanik  2,  No.  2:  110.  1904. 

Tetrapedia  setigera  Archer,  Quart.  Jour.  Micr.  Sci.  N.  S.  12:  365,  pi.  21, 
figs.  14-17.  1872;  Grevillea  1:  46,  pi.  3,  figs.  14-17.  1872;  G.  S.  West,  Brit. 
Freshw.  Algae  349.  1904;  de  Toni,  Sylloge  algarum  5:  113.  1907. 

Polyedrium  trigonum  var.  setigerum  (Archer)  Schroder,  Forschungsbr.  a.  d. 
Biol.  Stat.  zu  Plon  6:  23,  pi.  1,  fig.  6.  1898. 

Cells  small,  triangular,  flattened,  with  a conspicuous  emargination 
on  each  side  in  front  view.  Comers  of  cells  rounded  and  produced  into 
a long  delicately  tapering  spine.  Chloroplast  single.  Ailing  the  entire 
cell ; with  one  pyrenoid.  (Facultative  Planktont). 

Diam.  cells  (without  spine)  7-9  /x;  length  of  spines  12-15  /x. 

White  Ash  (r). 

G.  S.  West  and  de  Toni  follow  Archer  in  considering  this  organism 
a member  of  the  Myxophyceae  West  stating;  setigera  Archer  is  a 
beautiful  little  species  known  from  N.  W.  Scotland  and  W.  Ireland, 
which  has  been  erroneously  referred  by  some  authors  to  the  chlorophy- 
ceous  genus  Tetraedron.  The  cell  contents  of  Tetrapedia  setigera  are 
homogeneous  and  of  a pale  blue-green  color.”  The  cell  contents  of  the 
individuals  that  I have  observed  are  distinctly  grass  green  in  color 
and  contain  a single  pyrenoid.  This  pyrenoid  has  not  been  noted 
by  ell  her  Archer  or  Schroder.  Since  the  shape  and  dimensions  of 
the  cel's  that  I have  found  are  exactly  the  same  as  those  given  by 
Archer  I believe  that  I am  dealing  with  the  same  organism  that  he 
described  and  one  which  is  a member  of  the  Chlorophyceae  and  not 
the  Myxophyceae. 

var.  GRAciLE  (Reinsch)  de  Toni.  PI.  24,  Figs.  5-9. 

Sylloge  algarum  1:  598,  1889;  Printz,  Kgl.  Norske  Vidensk.  Selsk.  Skr.  1915, 
No.  4:  29,  pi.  3,  figs.  167-169.  1916. 

Polyedrium  trigonum  var.  gracile  Reinsch,  Die  Algenfl.  d.  mitt.  Th.  v. 
hh-anken  75:  pi.  3,  figs,  la-lb.  1867. 

Tetraedron  proteiforme  G.  M.  Smith  non  (Turner)  Brunnthaler,  Trans.  Wis. 
Acad.  Sci.,  Arts,  & Lett,  19':  632,  pi.  15,  figs.  4-5.  1918. 


118 


WISCONSIN  PHYTOPLANKTON 


Cells  triangular,  flattened,  concavity  of  sides  very  marked.  Angles 
of  cells  ending  in  short  spines.  Several  parietal,  disciform  chloroplasts 
without  pyrenoids.  (Facultative  Planktont). 

Cells  23-50  fx  broad ; 6-10  fi  thick. 

Blake  (rr),  Chain  (r),  Cochrane  (r),  Fishtrap  (rr),  Horse  (r),  Lac  Court 
Oreilles  (rr),  Little  Bear  (rr),  Little  Crooked  (rrr).  Loon  (rr),  Paddock  (rrr). 
Palmer  (rrr),  Rice  (1)  (rr),  Tenderfoot  (r).  Tied  Canoe  (rrr).  White  Ash 
(rr),  Wolf  (rr). 

In  the  second  list  of  Wisconsin  algae  this  alga  was  given  as  T.  pro- 
teiforme  but  I am  now  convinced  that  it  is  T.  trigonum  var.  gracUe. 
The  cells  reach  a much  larger  size  than  that  given  by  Reinsch  and  the 
excavation  of  the  sides  may  be  very  much  greater ; in  fact  the  cells  are 
at  times  so  delicate  that  they  might  be  placed  as  Cerasterias  species  had 
not  other  individuals  in  the  same  collection  the  ordinary  cell  shape  of 
T.  trigonum  var.  gracUe, 

Tetraedron  minimum  (A.  Braun)  Hansgirg.  PI.  24,  Figs.  10-13. 
Hedwigia  27:  131.  1888;  G.  S.  West,  Brit.  Freshw.  Algae  231,  fig.  101a.  1904. 

Cells  small,  flattened,  front  view  square  or  oblong  with  slightly 
rounded  corners  and  concave  sides.  Side  view  fusiform-elliptic.  Wall 
smooth  or  finely  granulate.  Chloroplast  single,  parietal,  with  one 
pyrenoid.  (Facultative  Planktont). 

Cells  6-20  fi  long,  5-8  fx  thick. 

Beaver  (2)  (rrr).  Camp  (rr),  Deer  (rrr),  Hillman  (rrr),  Horse  (rr),  Little 
Bass  (2)  (rrr).  Little  Doctor  (rr),  Mendota  (rrr),  Okauchee  (rrr),  Paddock 
(rrr).  Round  (3)  (rrr). 

Tetraedron  regulare  Kiitzing.  PI.  24,  Fig.  14. 

Phycol.  germanica  129.  1845. 

Polyedrium  tetraedricum  Nageli,  Gatt.  einz.  Algen  84,  pi.  4,  figs.  B3a-B3b. 
1849. 

Cells  medium  sized,  tetragonal,  generally  pyramidal,  sides  concave, 
straight,  or  slightly  convex.  Angles  with  a single,  heavy,  short,  blunt, 
spine.  ( Tychoplanktont ) . 

Diam.  cells  (with  spines)  14-45  fx. 

Blake  (rr). 

var.  INCUS  Teiling.  PI.  24,  Figs.  15-16. 

Sv.  Bot.  Tids.  6:  277,  274,  fig.  12.  1912. 

Polyedrium  regulare  Chodat  non  Kiitzing,  Mater,  pour  la  flore  crypt.  Suisse 
V:  220,  fig.  146.  1902. 

Cells  small,  tetragonal,  flattened  or  pyramidal,  sides  slightly  concave. 
Angles  produced  into  a single  short  delicate  straight  or  curved  spine. 
( Tychoplanktont) . 


WISCONSIN  PHYTOPLANKTON 


119 


Diam.  cells  (without  spine)  13-18  /a;  length  of  spines  7-8  /a. 

Poor  Farm  (rr). 

This  is  probably  what  Chodat  has  figured  as  T,  regulare.  It  differs 
from  the  typical  form  in  the  smaller  size,  constantly  concave  sides  of 
the  cell,  and  the  delicate  spines  at  the  cell  angles. 

var.  TORSUM  (Turner)  Brunnthaler.  PI.  24,  Figs.  17-18. 
in  Pascher,  Siisswasserfl.  Deutschl.,  osterr.  u.  d.  Schw.  5^:  150,  fig.  169.  1915. 

Cells  medium  sized,  tetragonal,  with  the  two  halves  of  the  cells 
cruciately  arranged.  Sides  of  cells  straight  or  convex.  Angles  of  cells 
with  a single  short  stout  spine  (Facultative  Planktont). 

Diam.  cells  25-40  /a. 

Horse  (sss). 

Over  a hundred  individuals  were  observed  in  the  plankton  catch 
from  this  lake  and  the  twisting  of  the  cell  halves  was  a very  constant 
character. 

Tetraedron  victorieae  var.  major  var.  nov.  PI  24,  Figs.  19-22; 

PI.  25,  Fig.  1. 

Cells  medium  sized,  four-sided,  with  two  deeply  emarginate  sides 
dividing  the  cell  into  two  cruciately  arranged  halves.  Sides  of  cells, 
in  vertical  view,  broadly  fusiform  with  acute  apices.  All  angles  of 
cells  with  a single  heavy  straight  spine  (Euplanktont). 

Cells  (with  spines)  30-60  /a  long;  15-20  /a  broad. 

Chain  (r). 

The  cell  shape  and  the  peculiar  twisting  of  the  two  halves  is  identical 
with  that  of  T.  victorieae  Woloszynska  (Hedwigia  55:  203,  pi.  6,  jigs. 
1-A:.  1914)  which  is  known  from  the  plankton  of  Lake  Victoria 

Nyanza,  Africa.  Measurement  of  about  25  Wisconsin  individuals  give 
the  following  variation  in  size,  length  30-60  /a,  breadth  15-20 ; whereas 
the  length  of  the  African  individuals  varies  from  20  to  30  /a  and  the 
breadth  10-15  /a. 

Tetraedron  verrucosum  G.  M.  Smith.  PI.  25,  Pigs.  2-3. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  632,  pi.  15,  figs.  1-2.  1918. 

Cells  large,  tetragonal,  pyramidate,  or  with  the  halves  cruciate.  Sides 
convex.  Angles  of  cell  terminating  in  a very  heavy,  blunt  spine.  Cell 
wall  thick,  verrucose.  (Euplanktont). 

Diam.  cells  (with  spines)  65-80  /a;  length  of  spines  13-18  /a. 

Bear  (1)  (rr). 


120 


WISCONSIN  PHYTOPLANKTON 


Tetraedron  caudatum  (Corda)  Hansgirg.  PI.  25,  Figs.  4-7. 
Hedwigia  27:  131.  1888;  G.  iS.  West,  Brit.  Freshw.  Algae  231,  fig-  101®.  1904. 

Cells  small,  flattened,  flve-sided;  four  of  the  sides  concave  and  the 
fifth  deeply  incised.  Angles  rounded  and  produced  into  a single 
straight  spine  that  lies  parallel  with  the  flat  side  of  the  cell.  (Tycho- 
planktont) . 

Diam.  cells  6-22  fx ; length  of  spines  1-3.5  /x. 

Ctiain  (rrr).  East  (rrr),  Dutchmans  (rrr).  Horse  (rr).  Lake  of  the  Woods 
(rrr),  Mendota  (rrr),  Palmer  (rrr).  Reserve  (rrr).  Wild  Goose  (rrr). 

The  notch  at  one  side  of  the  cell  varies  considerably  in  depth  but 
is  always  deeper  than  the  incurving  of  the  other  four  sides. 

var.  LONGispiNUM  Lemmermann.  PI.  25,  Pigs.  8-12. 

Bot.  Cent.  76:  151.  1898;  Forschungsbr.  a.  d.  Biol.  Stat.  zu  Flon  7:  117,  ph  1, 
figs.  8-9.  1899. 

Spines  on  corners  at  right  angles  to  the  flat  side  of  the  cell,  generally 
two  pointing  in  one  direction  and  three  in  the  other.  Spines  much 
longer  than  in  the  typical  form.  (Euplanktont). 

Diam.  cells  (without  spines)  8-18  /a;  length  of  spines  3-8  fi. 

Pine  Tree  (r),  Travis  (sss) 

This  is  a sharply  defined  variety,  differing  from  the  typical  form  in 
the  bending  of  the  spines  so  that  they  lie  at  right  angles  to  the  plane 
of  the  cell.  Lemmermann ’s  figure  9 shows  this  very  well  but  for  some 
reason  the  cell  in  his  figure  8 has  no  spines  and  so  is  not  at  all  charac- 
teristic. 

Tetraedron  pentaedricum  W.  & G.  S.  West.  PI.  25,  Figs.  13-17. 
Trans.  Linn.  Soc.  2nd  iSer.  Bot.  5:  84,  pi.  5,  figs.  15-16.  1895. 

Cells  small,  five-cornered,  with  four  corners  in  one  plane  and  the  fifth 
lying  at  an  angle  of  30-90  degrees.  Corners  subacute,  each  with  a 
single,  short,  curved  spine.  Chloroplast  single,  parietal,  with  one  pyre- 
noid.  (Facultative  Planktont). 

Diam.  cells  (without  spines)  5.5-14  fi,  (with  spines)  9-20  fx. 

Soft  (rr). 

T.  pentaedricum  has  not  been  observed  since  it  was  described  from 
Madagascar  by  the  Wests.  Chodat  considers  it  a synonym  of  T.  cau- 
datum (Corda)  Hansg.  erroneously  citing  it  as  Tetrapedia  pentaedri- 
cum (Mater,  pour  la  fl.  crypt.  Suisse  1^:  219.  1902).  Isolation  of  this 


WISCONSIN  PHYTOPLANKTON 


121 


alga  in  pure  culture  with  the  retention  of  its  distinguishing  character 
shows  that  the  Wests  are  correct  in  considering  it  a distinct  species. 
It  resembles  T.  caudatum  in  the  size,  number  of  corners,  character  of 
spines  at  the  corners,  and  the  concave  sides ; but  differs  in  having  four 
corners  in  approximately  the  same  plane  and  the  fifth  at  an  angle  with 
the  plane  of  the  other  four.  There  is  considerable  variation  in  the 
angle  at  which  this  fifth  corner  lies  but  it  is  never  in  the  same  plane  as 
the  other  corners.  The  Wests  (1.  c.  fig.  17)  also  describe  a variety 
minima  which,  as  the  name  implies,  is  smaller.  I find  that  the  variations 
in  size  of  cells  of  the  typical  form  in  a pure  culture  include  the  dimen- 
sions set  for  the  variety  minima  so  that  this  variety  cannot  be  recognized. 


Tetraedron  hastatum  (Reinsch)  Hansgirg.  PI.  25,  Fig.  18. 
Hedwigia  27:  132.  1888. 

Polyedrium  tetraedricum  var.  hastatum  Reinsch,  Die  Algenfl.  d.  mitt.  Th.  t. 
Franken  77,  pi.  5,  iigs.  3a-3b.  1867. 

Cells  medium  sized,  pyramidate,  with  the  angles  produced  into  long 
tapering  and  somewhat  concave  processes.  Processes  unbranched  but 
having  2 or  3 short  spines  at  the  tip.  (Tychoplanktont). 

Diam.  cells  (with  processes)  28-36  /a;  diam.  base  of  process  8 /jl. 

Horse  (rrr). 

The  general  shape  of  the  cell  is  similar  to  that  of  T.  limneticum  but 
there  is  no  branching  of  the  processes. 


var.  PALATiNUM  (Schmidle)  Lemmermann.  PI.  25,  Figs.  19-21. 

Ber.  d.  D.  hot.  Ges.  20:  (247).  1902. 

Polyedrium  hastatum  var.  palatinum  Schmidle,  Ber.  d.  D,  hot.  Ges.  18:  148, 
149,  pi.  6,  figs.  4-5.  1900. 

Cells  pyramidal,  with  convex  sides,  angles  produced  into  fairly  deli- 
cate non-tapering  processes  about  as  long  as  the  diameter  of  the  cells. 
Processes  unbranched  but  with  three  short  spines  at  the  apex.  (Ty- 
choplanktont) . 

Diam.  cells  (without  processes)  4^14  y.;  length  processes  about  10  fi. 

Horse  (rr). 

The  processes  at  the  angles  of  the  cell  do  not  seem  as  much  a part 
of  the  cell  as  in  the  typical  form.  Although  both  the  typical  form 
and  the  variety  palatinum  were  found  at  the  same  station  the  two  seem 
distinct  and  without  transition  forms. 


122 


WISCONSIN  PHYTOPLANKTON 


Tetraedron  constrictum  nom.  nov.  PI.  25,  Figs.  22-24. 

Tetraedron  arthrodesmiforme  var.  lohulatum  Woloszynska,  Hedwigla  55: 
203,  pi.  6,  fig.  11.  1914. 

Cells  medium  sized,  tetragonal,  flattened,  two  sides  straight  and  two 
opposite  sides  concave.  Angles  produced  into  narrow  slightly  taper- 
ing processes  which  give  the  cell  a decided  H-shape.  Ends  of  proc- 
esses generally  dichotomously  branched  the  branchlets  ending  in  two 
short  spines.  (Euplanktont). 

Diam.  cells  (without  processes)  5-8  /a;  length  18-25  fi;  thickness  8 fx. 
licngth  of  processes  10-15  (i. 

Bone  (rr). 

Woloszynska  has  found  these  peculiar  H-shaped  cells  in  the  plankton 
of  Lake  Victoria  Nyanza,  Africa  and  placed  them  among  other  varieties 
of  T.  arthrodesmiforme  described  at  the  same  time.  The  variety  lohu- 
latum  is,  however,  sufficiently  different  from  the  other  varieties  to  war- 
rant raising  it  to  speciflc  rank.  Bone  lake  is  the  only  station  where  it 
has  been  found  but  several  individuals  were  seen  in  the  catch  from 
this  lake. 

Tetraedron  gracile  (Reinsch)  Hansgirg.  PI.  26,  Figs.  1-5. 
Hedwigia  28:  19.  1889. 

Polyedrium  gracile  Reinsch,  Notarisia  3:  502,  pi.  7,  figs,  la-lc.  1888. 

Cells  medium  size,  conspicuously  flattened,  rectangular,  with  flattened 
sides.  Angles  of  cells  produced  into  narrow  processes  that  generally 
branch  twice  and  end  in  minute  spines.  The  primary  branchings  of 
the  processes  are  at  an  angle  of  90  degrees  with  one  another  and  always 
parallel  with  a side  of  the  cell.  Each  cell  containing  several,  parietal 
disciform  to  laminate  chloroplasts  without  pyrenoids.  (Euplanktont). 

Diam.  cells  (without  processes)  15-30  /a;  (with  processes)  35-80  fx) 
thickness  of  cells  6-12  /a. 

Bear  (1)  (rr).  Bear  Trap  (rrr),  Blake  (rr).  Chain  (rr),  Elizabeth  (rrr), 
Hillman  (sss).  Loon  (rrr).  Pine  (2)  (rr),  Poor  Farm  (rr).  Round  (rr),  Travis 
(r),  Wapagossett  (rr). 

Tetraedron  lobulatum  (Nageli)  Hansgirg.  PI.  26,  Figs.  6-7. 
Hedwigia  27:  132.  1888. 

Polyedrium  lohulatum  Nageli,  Gatt.  einz.  Algen  84,  pi.  4,  figs.  B4a-B4b.  1849. 

Cells  medium  sized,  tetragonal,  flattened,  or  pyramidal.  Processes 
of  angles  with  one  or  two  short  dichotomous  branchings  that  generally 
do  not  end  in  spines.  Sides  of  cells  distinctly  concave.  Cells  contain- 


WISCONSIN  PHYTOPLANKTON 


123 


ing  several  parietal  disciform  chloroplasts  without  pyrenoids.  (Tycho- 
planktont) . 

Diam.  cells  (with  processes)  30-40  fi. 

Birch  Island  (rrr),  Long  (3)  (rrr),  Sand  (2)  (rr). 

The  specimens  from  Sand  lake  were  of  particular  interest  since  three 
showed  the  production  of  autospores  (fig.  6).  The  chloroplast  of  old 
cells  are  frequently  indistinct  but  they  can  be  seen  quite  readily  in 
young  cells. 

var.  POLYFURCATUM  G.  M.  Smith.  PI.  26,  Fig.  8. 

Bull.  Torr.  Bot.  Cl.  43:  480,  pi.  26,  figs.  21-22.  1*916. 

Cells  tetragonal,  flattened  or  pyramidal;  with  concave,  straight,  or 
slightly  convex  sides.  Processes  at  angles  somewhat  tapering,  3-5  times 
dichotomously  branching,  the  ultimate  branchlets  with  2-3  minute 
spines.  (Facultative  Planktont). 

Diam.  cells  (without  processes)  15-25  fi,  (with  processes)  35-70  /x. 

Beaverdam  (r),  Blake  (rr).  Bone  (rr),  Clare  (rr),  Fish  (rr).  Loon  (rr), 
Muskallonge  (rrr).  Palmer  (r),  Pardee  (r),  Pine  Tree  (rr),  Rice  (1)  (rr). 
Shell  (rr).  Wild  Goose  (rrr). 

Differing  from  the  typical  form  in  the  greater  branching  of  the 
processes  and  from  T.  enorme  (Ralfs)  Hansg.  in  the  much  longer  proc- 
esses. 


Tetraedron  limneticum  Borge.  PI.  27,  Figs.  1-3. 

Bot.  Not.  1900:  5,  pi.  1,  fig.  2.  1900;  W.  & G.  S.  West,  Trans.  Roy.  Soc.  Edin- 
burgh 41:  507,  pi.  6,  figs.  10-11.  1905. 

Cells  of  medium  size,  tetragonal,  pyramidal,  the  four  angles  being 
produced  into  one  or  two  dichotomous  branchings.  Terminal  branch- 
lets  with  2-3  short  spines.  (Euplanktont). 

Diam.  cells  (with  processes)  45-85  p.;  diam.  base  of  processes  8-12  p. 

Chain  (rr),  Chetek  (r).  Clear  (r).  Crawling  Stone  (rrr).  Deer  (rr).  Diamond 
(rrr).  Island  (rr).  Kitten  (rr),  Little  Butternut  (rr).  Little  Crooked  (rrr), 
Mud  (2)  (r),  Nancy  (rr).  Palmer  (rr).  Pine  Tree  (rr).  Poplar  (rr).  Spirit 
(rrr).  Squirrel  (rr).  Wildcat  (rr).  Wild  Goose  (rrr).  Wolf  (rr). 

Tetraedron  planctonicum  G.  M.  Smith.  PI.  27,  Figs.  4-5. 

Bull.  Torr.  Bot.  Cl.  43  : 479,  pi.  26,  figs.  19-20.  1916. 

Cells  medium-sized,  four  to  five  sided,  sides  concave  to  convex.  Angles 
of  cells  produced  into  narrow,  once  to  twice  dichotomously  branched 
processes.  Ultimate  branchlets  with  2-3  short  spines.  Processes  broad 
in  front  view,  narrow  in  side  or  vertical  view.  (Euplanktont). 


124 


WISCONSIN  PHYTOPLANKTON 


Diam.  cells  (without  processes)  18-30  /x;  (with  processes)  45-60  /x. 

Cranberry  (rr),  Cochrane  (rr),  Devils  (2)  (sss),  Granite  (rr),  Horseshoe 
(1)  (rr),  Lindy  (rrr),  Lost  (rr),  No  Mans  (rr),  Prairie  (rr).  Rock  (rr).  Ver- 
milion (r). 

The  chief  difference  between  this  species  and  T.  Umneticum  is  the 
greater  size  of  the  cells  in  proportion  to  the  length  of  the  processes. 


Tetraedron  enorme  (Ralfs)  Hansgirg.  PI.  27,  Fig.  6. 
Hedwigia  27:  132.  1888;  G.  S.  West,  Brit.  Freshw.  Algae  231,  fig.  IOId.  1904. 

Cells  irregularly  tetrahedric,  angles  produced  into  short  processes 
and  sides  emarginate.  Processes  generally  bilobed  and  ending  in  short 
spines.  ( Tychoplanktont ) . 

Diam.  cells  25-45  fx. 

Carson  (rr),  Cochrane  (rr),  Devils  (2)  (r).  Horse  (rrr).  Horseshoe  (2) 
(rrr).  Lake  of  the  Woods  (rrr),  Okauchee  (rrr).  Pine  (2)  (rr). 


POLYEDRIOPSIS  Schmidle  1899. 

Cells  solitary,  generally  tetragonal,  flattened;  rarely  pyramidal  cr 
with  sides  cruciate.  Corners  truncate  and  with  3-10  long,  hyaline, 
slightly  tapering  setae.  Chloroplast  parietal  or  entirely  Ailing  the 
cell,  pyrenoid  single. 

Reproduction  by  the  formation  of  2-4-8  autospores  through  the  divi- 
sion of  the  cell  contents. 


PoLYEDRiOPSis  SPiNULOSA  Schmidle.  PI.  27,  Figs.  7-8, 

Allg.  Bot.  Zeitschr.  5:  17.  1899. 

Tetraedron  spinulosnm  Schmidle,  ibid.  2:  193,  fig.  2.  1896. 

Characters  the  same  as  those  of  the  genus.  (Euplanktont). 
Greatest  diameter  of  cells  12-25  fi ; length  of  setae  about  40  fi. 

Horse  (rr).  Prairie  (rrr). 

The  general  tendency  among  phycologists  is  to  follow  Wille’s  prac- 
tice and  place  the  alga  in  a special  sub-genus  of  Tetraedron.  The 
setae  on  the  cell  angles  are  of  the  same  type  as  those  found  on  Lager- 
heimia  and  Micractinium  so  that  Polyedriopsis  forms,  in  my  opinion, 
a genus  parallel  with  Tetraedron  just  as  Lagerheimia  does  with  Oocystis. 


WISCONSIN  PHYTOPLANKTON 


125 


Sub-family  MICEACTINIEAE. 

Cells  solitary  or  in  colonies;  spherical  or  ovoid;  with  long  hyaline 
setae  or  spines  completely  covering  or  restricted  to  certain  parts  of  the 
cell  wall.  Chloroplast  single  and  cup-shaped ; or  laminate  to  disciform 
and  from  one  to  several  in  each  cell.  Chloroplasts  generally  with  pyrv3- 
noids. 


KEY  TO  THE  GENERA. 


Cells  spherical. 

Cells  organized  into  definite  colonies Micractinium  (p.p.) 

Cells  solitary. 

Wall  covered  with  fine  hair-like  setae. 

Setae  thickened  in  lower  third Acanthospheaeba 

Setae  not  thickened  in  lower  third Golenkinia 

Wall  covered  with  delicately  tapering  spines Echinosphaerella 

Cells  ovoid. 

Cells  organized  into  definite  colonies Micractinium:  (p.p.) 

Cells  solitary. 

Setae  somewhat  tapering  Lagerheimia 

Setae  not  tapering  Franceia 


MICRACTINIUM  Fresenius  1858. 

Cells  spherical  or  ovoid,  in  colonies  of  4-32  or  more,  generally  quad- 
rately  arranged  in  one  plane  but  sometimes  tetrahedrically  disposed. 
Cell  wall  delicate,  with  1-7  long  hyaline  setae  that  are  not  thickened 
at  the  base  lying  on  the  free  surface  of  the  cells.  Chloroplast  single, 
parietal,  cup-shaped ; with  one  pyrenoid. 

Reproduction  by  the  division  of  contents  of  any  cell  to  form  a 4-  or 
8-celled  autocolony,  the  young  colony  being  liberated  by  a rupture  of 
the  mother  cell  wall  into  four  parts.  Young  coenobia  frequently  re- 
maining attached  to  the  parent  coenobe  for  some  time. 

KEY  TO  THE  SPECIES. 


Cells  spherical  M.  PusiixuM 

Cells  ovoid M.  Quadrispenum 

Micractinium  pusillum  Fresenius.  PL  28,  Figs.  IS. 

Abh.  Senckenb.  Naturf.  Ges.  2:  236,  pi.  11,  figs.  46-49.  1858;  G.  M.  Smith,  Bull. 
Torr.  Bot.  Cl.  43:  477,  pi.  25,  fig.  18.  1916. 

Richteriella  hotryoides  (Schmidle)  Lemmermann,  Hedwigia  37:  307,  pi.  10, 
figs.  1-6.  1898. 

Richteriella  hotryoides  forma  fenestrata  Chodat,  Mater,  pour  la  flore  crypt. 
Suisse  V:  194,  fig.  110.  1902. 


126 


WISCONSIN  PHYTOPLANKTON 


Richteriella  lotryoides  forma  tetraedrica  Lemmermann,  Arch.  f.  Hydrobiol. 
u.  Planktonkde.  5:  307.  1910. 

Colonies  of  4-8-16  or  more  cells  in  groups  of  four  and  disposed  in  a 
quadrate  or  pyramidate  manner  with  the  groups  of  four  in  turn  pyra- 
midately  or  quadrately  arranged.  Cells  spherical,  with  1-5  long,  hya- 
line, delicately  tapering  setae  on  the  face  not  adjacent  to  other  cells. 
Chloroplast  single,  parietal,  cup-shaped;  with  one  pyrenoid.  (Eu- 
planktont). 

Diam.  cells  (without  setae)  3-7  /x;  length  of  setae  20-35  /x. 

Blake  (rrr),  Bone  (sss),  Chain  (sss),  Chetek  (rr),  East  (rr),  Green  (1) 
(rr),  Hooker  (rr),  Horse  (rr),  Horseshoe  (2)  (rrr).  Island  (rrr),  Little  Bass 
(2)  (r).  Little  Crooked  (rrr).  Loveless  (r),  Mendota  (rr),  Monona  (cc).  North 
Turtle  (rr),  Pokegama  (3)  (rr).  Poor  Farm  (rr).  Pope  (rr),  Prairie  (rr), 
Round  (1)  (rr).  Tenderfoot  (rrr).  Tied  Canoe  (rr).  Wolf  (rrr). 

Flat  sixteen-celled  colonies  with  a central  open  space  are  the  most 
common.  Such  colonies  have  been  given  the  form  name  fenestrata  but 
both  it  and  the  form  tetraedrica  are  unworthy  of  recognition.  On  rare 
occasions  large  colonies  are  found;  colonies  containing  over  750  cells 
having  been  collected  from  the  plankton  of  Lake  Monona. 

var.  ELEGANS  G.  M.  Smith.  PI.  29,  Pig.  1. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19h  631,  pi.  12,  fig.  4.  1918. 

Cells  with  5-7  setae  on  the  exposed  face.  Dimensions  as  in  the 
typical  form.  (Euplanktont). 

Rice  (1)  (rr). 

This  seems  to  be  a distinct  variety  since  the  cells  of  colonies  from 
this  lake  all  bore  the  large  number  of  setae. 


Micractinium  quadrisetum  (Lemmermann)  G.  M.  Smith.  PI.  28, 

Fig.  4. 

Bull.  Torr.  Bot.  Cl.  43:  479,  pi.  25,  fig.  17.  1916. 

Cells  ovoid,  with  1-4  long,  delicately  tapering  setae  on  the  exposed 
faces.  Chloroplast  single,  parietal,  cup-shaped;  with  one  pyrenoid. 
(Euplanktont). 

Diam.  cells  (without  setae)  4-7  fi,  length  8-10  /x;  length  of  setae 
23-40  fx. 

Bear  Trap  (rrr).  Camp  (rr).  Cranberry  (rrr).  Eagle  (rrr). 

The  cells  of  this  species  are  somewhat  larger  than  those  of  M.  pusil- 
lum  and  are  distinctly  ovoid.  The  character  upon  which  the  specific 


WISCONSIN  PHYTOPLANKTON 


127 


name  is  based  is  quite  misleading  since  the  number  of  setae  may  vary 
from  one  to  four.  Colonies  containing  more  than  sixteen  cells  have 
not  been  observed  and  the  cell  arrangement  has  been  quadrate  in  every 
case. 

GOLENKINIA  Chodat  1894. 

Cells  spherical,  normally  solitary;  occasionally  forming  temporary 
colonies.  Cell  wall  thin,  sometimes  enclosed  in  a thin  gelatinous  en- 
velope. Surface  of  cell  covered  with  hyaline  setae  that  are  slightly 
tapering  but  not  conspicuously  thickened  in  the  lower  third.  Chloro- 
plast  single,  parietal  and  cup-shaped  or  entirely  filling  the  cell;  pyre- 
noid  single. 

Keproduction  by  the  formation  of  autospores.  Zoospores  have  been 
reported  but  their  formation  is  doubtful. 

KEY  TO  THE  SPECIES. 

Setae  25-45  long G.  Radiata 

Setae  12-18  long G.  Patjcispina 

Golenkinia  radiata  Chodat.  PI.  29,  Figs.  2-3. 

Jour,  de  Bot.  8:  305,  2)Z.  3,  figs.  1-24.  1894. 

Cells  spherical,  solitary,  sometimes  in  temporary  colonies  of  four 
cells.  Entire  cell  wall  covered  with  long,  delicate,  hyaline  setae.  Chlor- 
oplast  single,  cup-shaped,  parietal ; with  one  pyrenoid.  (Euplanktont) . 

Diam.  cells  (without  setae)  7-15  /x;  length  setae  25-45  /x. 

Green  (2)  (rrr),  White  Ash  (rr). 

This  and  the  following  Golenkinia  species  have  been  made  a sub- 
genus of  Micractinium  by  Wille  and  that  terminology  followed  in  the 
second  list  but  the  colonial  and  solitary  habit  seem  to  me  sufficiently 
diverse  to  v/arrant  generic  distinction. 

Golenkinia  paucispina  W.  & G.  S.  West.  PI.  29,  Figs.  4-5. 

Trans.  Roy.  Irish  Acad.  32,  Sec.  B:  68,  pi.  1,  fig.  18.  1902. 

Cells  solitary,  spherical,  with  few  to  fairly  numerous,  short,  delicately 
tapering,  hyaline  or  dark  setae.  Chloroplast  single,  completely  filling 
the  cell,  with  one  pyrenoid.  (Euplanktont). 

Diam.  cells  (without  setae)  15-18  /x;  length  setae  12-18  /x. 

Prairie  (rr). 

The  setae  of  the  cells  in  Prairie  lake  were  more  numerous  than  the 
Wests  found  them  in  individuals  from  the  plankton  of  Lough  Neagh, 


128 


WISCONSIN  PHYTOPLANKTON 


Ireland.  They  were  also  dark  colored  and  are  more  conspicuous  than 
in  other  members  of  the  Micractineae. 

ACANTHOSPHAERA  Lemmermann  1899. 

Cells  spherical,  solitary,  with  a single  cup-shaped  chloroplast  con-' 
taining  one  pyrenoid.  Cell  wall  thin,  without  a gelatinous  sheath; 
covered  with  many  long  hyaline  setae  that  are  thicker  in  the  lower 
third  and  then  abruptly  diminish  to  a very  fine  hair. 

Method  of  reproduction  unknown. 

Acanthosphaera  Zachariasi  Lemmermann.  PI.  29,  Figs.  6-8. 
Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  7:  118,  pi.  1,  figs.  10-11.  1899. 

Characters  as  those  of  the  genus.  (Euplanktont). 

Diam.  cells  (without  setae)  9-14.5  /x;  length  setae  30-35  /x. 

Horse  (rr). 

The  chief  distinction  between  this  genus  and  Golenkinia  is  the  thick- 
ening of  the  lower  part  of  the  setae. 

Echinosphaerella  gen.  nov. 

Cells  spherical,  solitary.  Cell  wall  thin,  completely  covered  with 
heavy,  long,  hyaline,  delicately  tapering  and  slightly  concave,  homo- 
geneous spines.  Chloroplast  single,  parietal,  cup-shaped;  with  one 
pyrenoid. 

Reproduction  unknown. 

Echinosphaerella  limnetica  sp.  nov.  PI.  29,  Figs.  9-11. 

Characters  as  described  above.  (Euplanktont). 

Diam.  cells  (without  spines)  9-12  fi.  Spines  2.5-3  /x  broad  at  base, 
20-25  fjL  long. 

Horse  (rr). 

The  alga  at  once  suggests  a desmid  zygospore,  especially  those  of 
certain  Staurastrum  species.  In  all  desmid  zygospores  the  chloroplast 
is  not  definite  and  since  the  alga  collected  from  Horse  Lake  has  a 
single,  well  defined,  cup-shaped  chloroplast  with  one  pyrenoid  the  pre- 
sumption is  that  it  is  a vegetative  cell  and  not  a zygospore.  The 
nearest  genus  is  Echinosphaeridium  Lemmermann  where  the  setae 
covering  the  wall  have  a broad  tapering  gelatinous  sheath  at  the  base. 
In  Echinosphaerella  there  is  not  a central  hair-like  seta  with  a gelati- 
nous covering,  but  a homogeneous  spine  of  considerable  thickness  at  the 


WISCONSIN  PHYTOPLANKTON 


129 


base.  Although  the  genus  is  provisionally  placed  in  the  Micractinieae 
its  spines  are  quite  different  from  those  of  other  genera  of  the  sub- 
family. 


LAGERHEIMIA  Chodat  1895. 

Cells  solitary;  ovoid,  ellipsoid,  or  citriform.  Cell  wall  firm,  without 
a gelatinous  sheath;  with  long  tapering  setae  that  lie  a short  distance 
back  from  the  poles  or  cover  the  entire  wall.  Chloroplasts  1-4,  pari- 
etal, laminate;  with  or  without  pyrenoids. 

Reproduction  by  autospores  that  are  generally  liberated  at  once  but 
which  may  remain  inside  the  old  mother  wall  a short  time. 

KEY  TO  THE  SPECIES.  _ 


Setae  covering  entire  cell  wall L.  Droescheri 

Setae  confined  to  poles  of  the  cell. 

Cells  lemon-shaped L.  Citriformis 

Cells  ovoid. 

Length  of  setae  more  than  double  that  of  cell L.  Longiseta 

Length  of  setae  less  than  double  that  of  cell. 

2- 4  setae  at  each  pole L.  Subsalsa 

3- 8  (generally  6)  setae  at  each  pole L.  Ciliata 


Lagerheimia  ciliata  (Lagerheim)  Chodat.  PI.  31,  Figs.  1-2. 
Nuova  Notarisia  10:  90.  1895. 

Oocystis  ciliata  Lagerheim,  ofvsers  Kgl.  Vet.-Ak.  Porh.  39,  No.  2:  76,  pi.  3, 
figs.  33-37.  1882. 

Chodatella  ciliata  (Lag.)  Lemmermann,  Hedwigia  37:  310.  1898. 

Cells  oblong-ovoid,  with  3-7,  hyaline,  delicately  tapering  setae  at 
each  pole.  Chloroplasts  1-4,  parietal,  laminate;  each  with  a single 
pyrenoid.  ( Euplanktont) . 

Breadth  of  cells  (without  setae)  6-18  ja;  length  (without  setae)  10- 
• 21  fi.  Setae  15-20  fx  long. 

Kegonsa  (rr),  Mendota  (sss). 

The  setae  of  this  species  are  not  in  definite  whorls  but  distributed  over 
the  entire  polar  region. 

var.  minor  (G.  M.  Smith)  comb.  nov.  PI.  31,  Fig.  3. 

Chodatella  ciliata  var.  minor  G.  M.  Smith.  Bull.  Torr.  Bot.  Cl.  43:  477, 
pi.  25,  fig.  16.  1916. 

Cells  ovoid,  with  6-8  setae  at  each  pole.  (Euplanktont). 

Diam.  cells  (without  setae)  6-7.5  /x;  length  (without  setae)  8-10  fx. 
Setae  about  20  /t  long. 

Muskallonge  (rr). 

9 


130 


WISCONSIN  PHYTOPLANKTON 


Lagerheimia  subsalsa  Lemmermann.  PI.  30,  Figs.  3-4. 

Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  6:  193,  pi.  5,  figs.  2-6.  1898. 

Chodatella  subsalsa  Lommermann,  Hedwigia  37:  310.  1898. 

Cells  ovoid,  with  2-4  delicate  setae  at  each  pole.  Chloroplast  single, 
laminate,  parietal;  with  one  pyrenoid.  (Euplanktont). 

Diam.  cells  (without  setae)  2.5-8  /x;  length  (without  setae)  5-12  fi. 
Setae  7.5-26  /x  long. 

Deer  (rrr),  Geneva  (rr). 

Lagerheimia  longiseta  (Lemmermann)  Printz.  PI.  30,  Figs.  8-9. 

Skr.  Vidensk.  i Kristiania,  Mat.-Naturv.  Kl.  1913%  No.  6:  60.  1914. 

Chodatella  longiseta  Lemmermann,  Hedwigia  37:  310,  pi.  10,  figs.  11-18. 
18’98. 

Cells  ellipsoid,  with  a whorl  of  4-10  long,  hyaline,  delicately  tapering 
setae  a short  distance  from  each  pole.  Chloroplast  single  ( ?),  parietal; 
without  a pyrenoid  (?).  (Euplanktont). 

Breadth  of  cells  (without  setae)  5-8  fi;  length  (without  setae)  9-13  ju. 
Setae  40-55  /x  long. 

White  Sand  (sss). 

The  exceedingly  long  setae  at  once  distinguish  the  species  from  all 
others.  The  arrangement  of  the  setae  in  a whorl  is  best  seen  in  an  end 
view  of  a cell. 

var.  major  var.  nov.  PI.  30,  Figs.  10-12. 

Cells  ovoid,  with  somewhat  pointed  ends.  With  a whorl  of  4-7  setae 
a short  distance  from  each  pole.  Cells  containing  1-2  laminate  pari- 
etal chloroplasts  each  with  a single  pyrenoid.  (Euplanktont). 

Breadth  of  cells  (without  setae)  12-15  /x;  length  (without  setae) 
15-22  fx.  Setae  45-60  fi  long. 

Blake  (rr).  Little  Bass  (2)  (rrr). 

The  variety  is  distinguished  from  the  typical  form  by  the  more 
pointed  and  larger  cells. 


Lagerheimia  citriformis  (Snow)  comb.  nov.  PI.  30,  Pigs.  1-2. 

Chodatella  citriformis  Snow,  Bull.  U.  S.  Pish  Comm.  22:  389,  pi.  2,  figs. 
8^-8’.  1903. 

Cells  ovoid  to  ellipsoid,  with  a small  obtuse  projection  at  each  pole. 
Poles  with  a whorl  of  4-8  long,  hyaline,  delicately  tapering  setae  at  the 


WISCONSIN  PHYTOPLANKTON 


131 


base  of  the  polar  projections.  Chloroplast  single,  parietal;  with  one 
pyrenoid.  ( Euplanktont) . 

Breadth  cells  (without  setae)  8-20  fi;  length  (without  setae)  13-23  fj.. 
Setae  25-35  fi  long. 

Horse  (rrr),  Kegonsa  (rrr). 

This  is  the  only  species  with  polar  projections  that  resemble  the 
polar  nodules  of  Oocystis. 

Lagerheimia  Droescheri  (Lemmermann)  Printz.  PI.  30,  Figs.  5-7. 

Skr.  Vidensk.  i Kristiania  Mat.-Naturv.  Kl.  1913%  No.  6:  60.  1914. 

Chodatella  Droescheri  Lemmermann,  Ber.  d.  D.  Bot  Ges.  18:  98,  ph  3,  fig.  12. 
1900. 

Cells  ovoid  to  ellipsoid;  with  numerous  hyaline  delicately  tapering 
setae  covering  the  entire  wall.  Cells  with  2-A  parietal,  laminate 
chloroplasts ; each  with  a single  pyrenoid.  (Euplanktont). 

Breadth  of  cells  (without  setae)  5-12  fi;  length  (without  setae)  9-16 
fi.  Setae  15-22  long. 

Horse  (rrr),  Travis  (r).  Upper  Nashotah  (rr). 

FEANCEIA  Lemmermann  1898. 

Cells  ovoid,  solitary  or  in  colonies  of  2-4;  free-floating.  Cells  en- 
closed in  a delicate  gelatinous  sheath  (?).  Entire  cell  wall  covered 
with  delicate  hyaline  setae  that  do  not  taper.  Chloroplasts  1-3,  pari- 
etal, laminate,  with  or  without  pyrenoids. 

Eeproduction  by  autospores. 

Franceia  ovalis  (France)  Lemmermann.  PI.  31,  Fig.  4. 
Hedwigia  37:  308.  1898. 

Phythelios  ovalis  Franc6,  Notarisia  1894:  2,  figs.  1-5.  1894. 

Cells  ovoid  to  elliptic;  with  two  chloroplasts.  (Euplanktont). 
Breadth  of  cells  (without  setae)  7-10  /x;  length  (without  setae)  13- 
17  fx.  Setae  15-23  fx  long. 

Pine  Tree  (rr). 

The  minimal  dimensions  given  above  are  somewhat  smaller  than  those 
given  by  France  but  I feel  that  the  Wisconsin  organism  should  not  be 
considered  a distinct  variety  until  the  variation  in  size  of  the  typical 
form  has  been  determined -more  fully. 

The  recognition  of  the  genus  Franceia  is  open  to  question  since  the 
characters  upon  which  Lemmermann  bases  the  genus  (number  of 


132 


WISCONSIN  PHYTOPLANKTON 


chloroplasts,  presence  of  a vacuole,  and  cell  division  in  one  plane)  are 
ones  which  might  be  found  in  any  Lagerheimia  species.  The  setae, 
however,  are  very  delicate  and  do  not  taper  so  that  the  genus  is  pro- 
visionally considered  distinct  from  Lagerheimia. 

Sub-family  SELENA8TREAE. 

Cells  elongate,  straight  or  curved;  with  finely  pointed  ends  or  with 
ends  rounded.  Solitary  or  associated  in  colonies  containing  an  indefi- 
nite number  of  cells.  Colonies  with  or  without  a gelatinous  envelope. 
Cells  generally  with  one  parietal  chloroplast  that  is  with  or  without 
pyrenoids. 


KEY  TO  THE  GENERA. 


Cells  solitary. 

Ends  of  cells  produced  into  setae Schroedebia 

Ends  of  cells  not  produced  into  setae. 

Chloroplast  with  an  axial  row  of  pyrenoids Closteriopsis 


Chloroplast  never  with  more  than  a single  pyrenoid . Ankistrodesmus  (p.  p.) 
Cells  in  colonies. 

Colonies  not  enclosed  in  a gelatinous  sheath. 

Cells  straight,  in  loose  fasiculate  bundles  or  spirally 

twisted  around  one  another Ankistrodesmus  (p.  p.) 


Cells  curved,  with  convex  faces  towards  one  another Selenastbum 

Colonies  enclosed  in  a gelatinous  sheath. 

Cells  curved Kirchneriella 

Cells  straight. 

Colonies  with  cells  in  groups  of  two Elaktothrix 

Colonies  with  cells  in  groups  of  2-4-8 Quadrigula 


SELENASTRUM  Reinseh  1867. 

Cells  broadly  to  narrowly  acicular,  semilunar;  joined  by  their  con- 
vex faces  into  colonies  of  4^8-16  or  more  cells  without  a gelatinous  en- 
velope. Chloroplast  single,  parietal,  laminate,  on  convex  side  of  young 
cells ; entirely  filling  older  cells ; with  one  pyrenoid. 

Reproduction  by  any  cell  forming  2-4-8  autospores  which,  when 
liberated,  have  the  arrangement  of  the  cells  in  an  adult  colony.  Auto- 
spores remaining  attached  to  parent  colony  for  some  time. 

The  statement  is  generally  made  that  there  are  not  more  than  six- 
teen cells  in  a colony  but  I have  found  that  in  the  plankton  of  Wiscon- 
sin lakes  the  colonies  sometimes  contain  over  a hundred  cells. 


WISCONSIN  PHYTOPLANKTON 


133 


KEY  TO  THE  SPECIES. 


Cells  arcuate,  never  sickle-shaped S.  Westh 

Cells  arcuate  to  sickle-shaped. 

Diameter  of  cells  not  exceeding  5 ai S.  Geacile 

Diameter  of  cells  5-8  S.  Bibbaianum 


Selenastrum  gracile  Keinsch.  PI.  31,  Fig.  5. 

D.  Algenfl.  d.  mitt.  Th.  v.  Franken  65,  pi,  4,  figs.  3a-3b.  1867. 

Cells  lunate  to  sickle-shaped,  quite  narrow  in  proportion  to  their 
length.  Apices  of  cells  acute.  Chloroplast  single,  laminate,  parietal, 
on  convex  side  of  cell.  Without  a pyrenoid.  (Facultative  Planktont). 

Diam.  cells  3-5  p, ; length  15-30  fx.  Distance  between  apices  8-20  p. 

Bear  (3)  (rr),  Chain  (rr),  Hillman  (rrr).  Horse  (rr),  Monona  (r), 

Pokegama  (1)  (rr),  Prairie  (rr).  Upper  Turtle  (rrr),  Whitefish  (rr). 

Differs  from  the  next  species  in  the  more  delicate  cells.  Possibly  it 
should  be  considered  a variety  of  S.  Bihmianum  and  not  a distinct 
species. 

Selenastrum  Bibraianum  Reinsch.  PI.  31,  Figs.  6-7. 

D.  Algenfl.  d.  mitt.  Th.  v.  Franken  64,  pi.  4,  figs.  2a-2b.  1867. 

Cells  in  spherical  to  ovoid  colonies  of  4-8-16  or  more  with  their  con- 
vex sides  facing  the  center  of  the  colony.  Cells  crescent-shaped  lo 
sickle-shaped,  gradually  tapering  to  a fairly  sharp  apex.  Chloroplast 
parietal,  on  convex  side  of  and  almost  filling  the  cell ; pyrenoid  single. 
(Facultative  Planktont). 

Diam.  cells  5-8  p ; length  20-38  p.  Distance  between  apices  5-25  p. 

Beaverdam  (rr),  Blake  (rrr).  Bone  (rr),  Deer  (rrr),  Little  Bass  (2)  (rrr), 
Loveless  (rr),  Mendota  (rrr),  Meta  (r),  Nancy  (rr),  Pewaukee  (rr),  Pine 
Tree  (rr).  Poor  Farm  (rr).  Rice  (1)  (rr).  Spirit  (rrr).  Squirrel  (rrr),  Ten- 
derfoot (rr),  Travis  (rr).  White  Ash  (sss),  Wolf  (rr). 

All  descriptions  of  S.  Bibraianum  state  that  there  are  but  four  or 
eight  cells  in  the  colony  but  I have  found  that  in  Wisconsin  lakes  there 
may  be  over  a hundred  cells  in  the  colony,  the  number  of  cells  usually 
ceasing  to  be  a multiple  of  two  after  there  are  more  than  sixteen  cells 
in  the  colony. 

Selenastrum  Westii  sp.  nov.  PI.  31,  Figs.  8-10. 

Selenastrum  acuminatum  G.  S.  West  non  Lagerheim,  Jour,  of  Bot.  50  : 88, 
figs.  5a-5&.  1912. 

Colonies  of  2-4-8  cells  irregularly  arranged  with  their  convex  sides 
in  apposition.  Frequently  dissociating  into  the  individual  cells  when 


WISCONSIN  PHYTOPLANKTON 


.r.ature.  Ceils  innate  to  arcuate,  never  sickle-shaped;  gradually  taper- 
ing to  a shaj’p  point.  Chloroplast  single,  parietal  on  convex  side  of  cell ; 
without  a pyrenoid.  (Facultative  Planktont). 

Diam.  cells  1. 5-2.5  /a.  Distance  between  apices  15-18  /x. 

Devils  (1)  (rr). 

The  cells  of  this  species  are  quite  like  those  of  Scenedesmus  acumi- 
natus  (Lagerheim)  Chodat  but  their  organization  in  the  colony  is  quite 
different.  West  has  recently  investigated  an  organism  which  he  con- 
siders identical  with  the  Selenastrum  acuminatum  described  by  Lager- 
heim. I have  obtained  West’s  organism  in  pure  culture  and  find  that 
the  cell  shape  and  colony  organization  is  as  he  describes.  The  fortunate 
rediscovery  of  Lagerheim ’s  species  from  the  plankton  of  Horse  Lake 
shows  that  in  the  organization  of  the  colony  it  is  a Scenedesmus  and 
that  Chodat  is  entirely  correct  in  removing  the  species  from  Selenast- 
rum. The  organism  that  West  found  is,  on  the  other  hand,  a true 
Selenastrum  but  is  not  the  species  which  Lagerheim  erroneously  re- 
ferred to  Selenastrum. 

ANKISTRODESMUS  Corda  1838. 

Cells  acicular  to  fusiform ; straight,  lunate,  or  sigmoid ; ends  of  cells 
gradually  tapering  to  a point;  solitary  or  loosely  aggregated  without 
order  in  temporary  colonies  that  are  not  embedded  in  a gelatinous  en- 
velope. Chloroplast  single,  parietal,  sometimes  fragmented  into  small 
pieces ; with  or  without  a pyrenoid. 

Reproduction  by  the  formation  of  several  autospores  in  any  cell. 

KEY  TO  THE  SPECIES. 


Cells  twisted  around  one  another A.  Spiralis 

Cells  not  twisted  around  one  another A.  Falcatus 


Ankistrodesmus  falcatus  (Corda)  Ralfs.  PL  32,  Pig.  1. 

Brit.  Desmidieae  180,  pi.  34,  figs.  3a-3b.  1848;  G.  S.  West,  Brit.  Freshw.  Algae 
223,  fig.  94a.  1904. 

Cells  acicular  to  narrowly  fusiform,  tapering  very  gradually  to  acute 
apices,  lunate  or  slightly  arcuate.  Length  12-24  times  the  diameter. 
Seldom  solitary,  generally  loosely  associated  in  fasiculate  bundles. 
Chloroplast  single,  generally  without  pyrenoids.  (Facultative  Plank- 
tont) . 

Diam.  cells  1.5-3. 5 fx;  length  20-80  fx. 

Fence  (rrr).  Half  Moon  (rrr),  Horse  (rr),  Kawaguesaga  (rrr),  Lac  du 
Flambeau  (rrr).  Little  Crooked  (rr).  Lost  (rr),  Oconomowoc  (rrr),  Pine 


WISCONSIN  PHYTOPLANKTON 


135 


Tree  (rr),  Poor  Farm  (rr),  Poplar  (rr),  Rock  (1)  (rr),  Tenderfoot  (rr), 
White  Ash  (rr). 

var.  ACicuLARis  (A.  Braun)  G.  S.  West. 

Brit.  Freshw.  Algae  223,  figs.  94b-94o.  1904. 

Cells  usually  solitary,  straight  or  slightly  curved,  apices  acutely  at- 
tenuated. Chloroplast  single,  parietal,  with  or  without  a pyrenoid. 

Cells  2.5-4  fi  broad,  36-65  /x  long. 

Beaverdam  (rr),  Little  Bass  (1)  (rrr),  Mendota  (rr).  Rice  (1)  (rr),  Wau- 
besa  (rrr). 

var.  TUMiDus  (W.  & G.  S.  West)  G.  S.  West.  PI.  32,  Fig.  2. 

Brit.  Freshw.  Algae  224,  fig.  94d.  1904. 

Cells  solitary  or  in  small  aggregates,  straight  or  curved,  inflated  at 
the  middle  and  with  acute  apices.  Chloroplast  single,  parietal,  with 
or  without  pyrenoids.  (Tychoplanktont). 

Cells  4.5-6.S  /a  broad;  61-73  fi  long. 

Devils  (1)  (rrr),  Mendota  (rr). 

var.  MiRABiLis  (W.  & G.  S.  West)  G.  S.  West.  PI.  32,  Figs.  3-5. 
Brit.  Freshw.  Algae  224,  fig.  94b.  1904. 

Cells  solitary,  straight,  lunate,  or  sigmoid;  with  acute  apices;  much 
longer  and  narrower  than  the  typical  form.  Chloroplast  single,  com- 
monly fragmented  by  large  vacuoles  in  the  cytoplasm;  without  pyre- 
noids. ( Euplanktont ) . 

Cells  2-3.5  /A  broad ; up  to  150  /a  long. 

Bear  (3)  (rr),  Bryer  (rr),  Chain  (sss).  Crab  (rrr).  Devils  (1)  (sss). 
Devils  (2)  (rr).  Dummy  (rr),  High  (rr).  Horseshoe  (1)  (rr).  Reserve  (rr). 
Squirrel  (rr),  Travis  (rrr),  Whitefish  (rr). 


Ankistrodesmus  spiralis  (Turner)  Lemmermann.  PI.  32,  Figs.  6-7. 

Arch.  f.  Hydrobiol.  u.  Planktonkde.  4:  176.  1908. 

Raphidium  spirals  Turner,  Kgl.  Sv.  Vet.-Ak.  Handl.  25,  No.  5:  156,  pi.  20, 
fig.  26.  1892. 

Ankistrodesmus  falcatus  var.  spiralis  (Turner)  G.  S.  West,  Brit.  Freshw. 
Algae  224.  1904. 

Cells  acicular,  attenuated  to  acute  apices ; in  colonies  of  four  or  eight 
and  spirally  twisted  around  one  another  in  the  middle  of  the  cell  but 
with  the  extremities  free.  Chloroplast  single,  completely  filling  the 
cell;  without  a pyrenoid  ( ?).  (Tychoplanktont). 


136 


WISCONSIN  PHYTOPLANKTON 


Cells  1-2.5  ^ broad ; 20-40  long. 

Grassy  (rr),  Silver  (2)  (rrr). 

G.  S.  West  places  the  alga  as  a variety  of  A.  falcatus  but  the  twist- 
ing of  the  cell  seems  to  be  such  a constant  character  that  I have  fol- 
lowed Lemmermann’s  practice  in  considering  it  a distinct  species. 


CLOSTERIOPSIS  Lemmermann  1898. 

Cells  solitary,  acicular,  with  ends  produced  into  very  acute  apices, 
without  a gelatinous  envelope.  Chloroplast  single,  not  interrupted 
at  the  center  of  the  cell,  occupying  the  greater  portion  of  the  cell  and 
containing  a single  axial  row  of  about  a dozen  pyrenoids. 

The  genus  is  very  closely  related  to  Ankistrodesmus,  differing  onh^ 
in  the  greater  length  of  the  cells  and  the  axial  row  of  pyrenoids.  It 
also  resembles  certain  Closteriwn  species  but  the  chloroplast  of  Closter- 
ium  is  always  interrupted  at  the  center  of  the  cell.  Many  feel  that  the 
single  species  is  not  sufficiently  differentiated  to  warrant  its  separation 
from  Ankistrodesmus, 


CLOSTERIOPSIS  LONGissiMA  var.  TROPICA  W.  & G.  S.  West.  PI.  32,  Fig.  8. 

Trans.  & Proc.  Bot.  Soc.  Edinb.  23:  31,  pi.  1,  fig.  1.  1905. 

RhapTiidium  longissimum  var.  tropicum  W.  & G.  S.  West,  Trans.  Linn.  Soc. 
2nd.  Ser.  Bot.  6:  198.  1902. 

Cells  acicular,  poles  acute  but  not  ending  in  a point  of  hair-like  fine- 
ness. (Facultative  Planktont). 

Cells  6-7.5  fx  broad ; 225-370  /a  long. 

North  Turtle  (rr). 

The  dimensions  of  specimens  that  I have  found  agree  with  those  given 
for  individuals  from  Ceylon  but  not  with  those  from  the  Scotch  plank- 
ton. 


SCHROEDERIA  Lemmermann  1898. 

Cells  solitary,  straight  or  curved,  acicular;  with  one  apex  produced 
into  a fine  seta  tapering  to  a point,  the  other  with  a slightly  broader 
projection  terminating  in  a small  disc.  Cells  without  a gelatinous  en- 
velope. Chloroplast  single,  parietal,  laminate;  with  one  pyrenoid. 

Method  of  reproduction  unknown. 


WISCONSIN  PHYTOPLANKTON 


137 


ScHROEDERiA  SETiGERA  (Schroder)  Lemmermann.  PI.  32,  Fig.  12. 

Hedwi^ia  37:  311.  1898;  G.  M.  Smith,  Bull.  Torr.  Bot.  Cl.  43:  473,  pZ.  24, 
fig.  8.  1916. 

Length  of  cells  15-20  times  breadth.  (Enplanktont). 

Cells  3-6  fi  broad,  60-85  /a  long  (with  spines).  Length  of  spines 
13-27  fi. 

Chain  (sss).  Devils  (1)  (c).  Long  (2)  (rr).  Sand  (1)  (rr). 

This  peculiar  alga  has  the  general  appearance  of  a Characium.  Al- 
though hundreds  of  individuals  have  been  found,  it  has  never  been 
found  attached  to  other  algae  or  to  crustaceans  so  that  it  seems  safe 
to  assume  that  it  leads  a free-floating  and  not  an  epiphytic  existence. 
The  disc  at  one  end  of  the  setae  described  above  has  not  been  observed 
by  other  investigators,  possibly  because  the  alga  is  very  minute. 

Reproductive  stages  have  never  been  found  so  that  the  systematic 
position  of  the  genus  is  doubtful.  Judging  by  the  cell  shape  it  is  a 
close  relative  of  Ankistrodesmus,  a genus  to  which  it  has  been  referred 
by  some. 

ScHROEDERiA  JuDAYi  G.  M.  Smith.  PI.  32,  Figs.  9-11. 

Bull.  Torr.  Bot.  Cl.  43:  474,  pZ.  24,  Ms.  9-11.  1916. 

Cells  smaller  than  the  foregoing.  (Euplanktont). 

Cells  2.5-6  II  broad,  45-63  /t  long  (with  spines).  Length  of  spines 

10-16  /X. 

Amicoy  (rr),  Birch  (rrr),  Camp  (rr),  Delavan  (rr),  Kawaguesaga  (rr), 
Mendota  (sss),  Prairie  (rr).  Round  (1)  (rrr),  St.  Croix  (rr). 


QUADRIGULA  Printz  1915. 

Cells  generally  in  groups  of  2-4-8  with  their  long  axes  parallel  to 
the  long  axis  of  the  colony  and  enclosed  by  a hyaline,  homogeneous, 
gelatinous  sheath.  Colonies  ellipsoid,  2-5  times  as  long  as  broad.  Cells 
cylindrical  to  fusiform,  A-1  times  as  long  as  broad,  straight  or  slightly 
curved.  Chloroplast  single,  filling  most  of  the  cell;  with  or  without 
pyrenoids. 

Reproduction  by  2-4-8  autospores  from  each  cell,  the  fasiculate  group 
of  autospores  frequently  remaining  within  the  envelope  of  the  mother 
colony  for  some  time. 


138 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  SPECIES. 


Ends  of  cells  rounded Q.  Pfitzeri 

Ends  of  cells  pointed. 

Chloroplast  notched  at  the  center Q.  Chooati 

Chloroplast  not  notched  at  the  center Q.  Lacustbis 


Quadrigfula  Pfitzeri  (Schroder)  comb.  nov.  PL  33,  Figs.  1-2. 

Rhaphidium  Pfitzeri  Schroder,  Verb.  d.  Nat.-Med.  Ver.  zu  Heidelberg  N.  F. 
7:  152,  pi.  6,  fig.  6.  1902. 

Ankistrodesmus  Pfitzeri  (Schroder)  G.  S.  West,  Brit.  Freshw.  Algae  224, 
figs.  94g-94h.  1904. 

Cells  about  7 times  as  long  as  broad,  central  portion  cylindrical  with 
ends  slightly  tapering  and  rounded.  Chloroplast  generally  filling  the 
entire  cell,  with  or  without  a pyrenoid.  (Euplanktont). 

Breadth  of  cells  3-6  /x,  length  22-45  (generally  about  35)  p.. 

Bear  (1)  (rr),  Beaver  dam  (rr),  Blake  (rr).  Chain  (rr).  Clear  (rr), 

Cochrane  (sss).  Devils  (1)  (s),  Fishtrap  (rrr),  Found  (r),  Fowler  (rr), 
Harris  (rr),  Hillman  (ss),  Jennie  (rr).  Lac  Court  Oreilles  (rr),  Lindy  (rr). 
Long  (2)  (rrr).  Little  Wood  (rr).  Mud  (1)  (rr),  Mudhen  (rr),  Oconomowoc 
(rr),  Okauchee  (rr).  Palmer  (sss),  Pardee  (rr).  Pine  Tree  (r),  Poplar  (r). 
Reserve  (rr).  Rice  (1)  (rr).  Sand  (1)  (rr).  Shell  (rr),  tSishebogema  (rr), 
Travis  (rr).  White  Ash  (r),  Whitefish  (rr).  Wild  Goose  (rrr). 

The  chief  characteristic  of  the  genus  is  the  arrangement  of  the  cells 
in  groups  of  2-4-8  with  their  long  axes  parallel  to  the  long  axis  of  the 
colony,  together  with  the  gelatinous  envelope  that  surrounds  the  colony. 
Admitting  the  generic  validity  of  Quadirigula,  Ankistrodesmus  Chodati 
and  A.  lacustris  are  in  a much  more  natural  position  when  placed  with 
Quadrigvla  species. 

Quadrigula  Chodati  (Tanner-Fullman)  comb.  nov.  PL  33,  Fig.  3. 

Raphidium  Chodati  Tanner-Fullman,  Bull.  Herb.  Boiss.  2 Ser.  6:  156,  figs. 
1-11.  1906. 

Ankistrodesmus  Chodati  (Tanner-Fullman)  Brunnthaler,  in  Pascher,  Siiss- 
wasserfl.  Deutschl.,  osterr.  u.  d.  Schw.  5":  193,  fig.  306.  1915. 

Cells  linear,  arcuate,  or  lunate ; fusiform  and  tapering  to  sharp  ends. 
Longitudinally  arranged  in  a gelatinous  colony  of  4-8-16  or  more  cells. 
Cells  with  a single,  parietal,  laminate  chloroplast  that  is  notched  at 
the  center  and  contains  two  pyrenoids.  (Euplanktont). 

Breadth  of  cells  3.5-7  p,  length  30-80  p.  Colonies  up  to  50x250  p. 

Boulder  (r).  Little  Bass  (2)  (rrr).  Lac  du  Flambeau  (rr).  Sand  (3)  (ss). 

Tanner-Fullman  states  that  the  cells  are  always  lunate  but  those  that 
T have  observed  were  always  straight  or  slightly  curved.  The  notching 
of  the  chloroplast  together  with  the  two  pyrenoids  is  such  a distinct 


WISCONSIN  PHYTOPLANKTON 


139 


feature  that  there  can  be  no  doubt  of  the  identity  of  the  Wisconsin  alga 
with  his  species. 

Quadrigula  lacustris  (Chodat)  comb.  nov.  PL  33,  Figs.  4-6. 

Raphidium  Braunii  var.  lacustre  Chodat,  Bull.  Herb.  Boiss.  5:  pi.  11,  figs. 
9-10.  1897;  Mater,  pour  la  fl.  crypt.  Suisse  1^:  200,  fig.  117.  1902. 

AnTcistrodesmus  lacustre  (Chodat)  Ostenfeld,  Hedwigia  46:  384.  1907. 

Cells  spindle-shaped,  straight,  with  pointed  ends.  Cells  rarely  soli- 
tary, generally  irregularly  distributed  throughout,  or  in  groups  with 
their  long  axes  parallel  to  the  long  axis  of  the  fusiform  gelatinous 
colonial  envelope.  Chloroplast  single,  parietal,  laminate,  at  one  side 
of  the  cell  or  spirally  twisted;  generally  with  a single  pyrenoid.  (Eu- 
planktont). 

Cells  3-5  fjL  broad,  20-25  /a  long. 

Blue  Gill  (rr).  Browns  (rr).  Clear  Crooked  (cc).  Green  (2)  (rr).  Horseshoe 
(1)  (rr).  Lynx  (rr),  Pokegama  (2)  (rr).  Round  (1)  (rrr). 

ELAKTOTHRIX  Wille  1898. 

Cells  fusiform  when  mature,  longitudinally  arranged  in  pairs  within 
a fusiform  homogeneous  gelatinous  matrix.  Chloroplast  single,  laminate, 
parietal,  with  one  or  two  pyrenoids.  Colonies  epiphytic  when  young 
and  free-floating  when  mature;  or  free-floating  throughout  the  life  of 
the  plant. 

Reproduction  by  a transverse  division  into  two  daughter  cells  which 
remain  unchanged  for  some  time.  Akinetes  known. 

Wille  first  placed  the  alga  as  a close  relative  of  Actinastrum  Hantz- 
schi  Lagerheim,  but  later  thought  it  a relative  of  Coccomyxa  Schmidle 
(Wille,  in  Engler  & Prantl,  Nat.  Pflanzenfam.  V (Nachtr.) : 36,  figs. 
18^-18®.  1909) ; Pascher  (Susswasserfl.  Deutschl.,  Osterr.  u.  d.  Schw. 

5^:  220,  figs.  25-26.  1915)  places  it  among  the  algae  of  doubtful  sys- 
tematic position;  while  G.  S.  West  (Algae  1:  202.  1916)  thinks  it 
closely  allied  to  Ankistrodesmus,  a view  which  seems  to  me  most  logical 
since  Ankistrodesmus,  Quadrigtda  and  Elaktothrix  form  a very  natural 
evolutionary  series. 


KEY  TO  THE  SPECIES. 


Both  poles  of  cells  acute E.  Viridis 

One  pole  of  cell  acute,  the  other  generally  rounded E.  Gelatinosa 


Elaktothrix  gelatinosa  Wille.  PI.  34,  Figs.  1-3. 

Biol.  Cent.  18:  302.  1898;  in  Engler  & Prantl,  Nat.  Pflanzenfam.  1*  (Nachtr.) : 
36,  figs.  18a-18b.  1909;  W.  & G.  S.  West,  The  Naturalist,  1909:  291,  figs.  6a-6d. 
1909. 

Colonies  free-floating,  elongate  fusiform  to  somewhat  irregular ; with 


140 


WISCONSIN  PHYTOPLANKTON 


the  long  axes  of  the  cells  parallel  to  the  long  axis  of  the  colony.  Cells 
lying  in  pairs,  spindle-shaped;  generally  with  one  pole  rounded  and 
the  other  pointed.  The  rounded  ends  of  a pair  of  cells  in  apposition. 
Chloroplast  single,  parietal,  laminate;  with  one  pyrenoid.  Colonies 
rarely  containing  over  fifty  cells.  (Euplanktont). 

Cells  3-6  fx  broad;  15-25  /a  long.  Colonies  10-30  fx  broad;  70-160 
fi  long. 

Crooked  (rrr),  Deer  (rrr),  Hillman  (rr),  Jag  (rrr),  Jennie  (rr),  Long  (2) 
(rrr),  Long  (3)  (rr),  Loon  (rrr),  Mudhen  (rr).  Pine  (2)  (rrr).  Sand  (2) 
(rrr),  Streitor  (sss). 

The  dimensions  of  the  cells  and  the  general  appearance  of  the  colony 
in  individuals  that  I have  found  is  more  like  the  Wests’  description  of 
the  alga  as  found  in  England.  Wisconsin  colonies  rarely  contain  more 
than  sixteen  cells. 

Elaktothrix  viridis  (Snow)  Printz.  PI.  33,  Fig.  7. 

Skr.  Vidensk.  i Kristiania  Mat.-Naturv.  Kl,  1913^:  No.  6:  31,  pi.  1,  figs.  9-12. 
1914. 

Fusola  viridis  Snow,  Bull.  U.  S.  Fish  Comm.  22  : 389,  pi.  2,  figs.  VP-VP.  1903. 

Colony  free-floating  or  epiphytic,  fusiform  or  irregular;  gelatinous 
sheath  of  colony  sharply  defined,  frequently  showing  remains  of  old  ' 
cell  wall  at  apex.  Cells  broadly  fusiform,  straight  or  sigmoid,  with 
acute  apices.  Chloroplast  single,  completely  filling  the  cell;  with  one 
or  two  pyrenoids.  (Tychoplanktont) . 

Cells  6-15  II  broad,  12-35  /x  long. 

Soft  (rr). 


KIRCHNEKIELLA  Schmidle  1893. 

Cells  lunate  to  sickle-shaped  with  their  apices  almost  touching;  or 
elongate,  vermiform,  arcuate,  or  spiral  cylinders  with  rounded  ends. 
Associated  without  definite  arrangement  in  colonies  enclosed  by  a hya- 
line, homogeneous,  gelatinous  envelope.  Number  of  cells  in  young 
colonies  a multiple  of  two,  in  older  colonies  indefinite  but  rarely  more 
than  seventy-five.  Chloroplast  single,  parietal,  on  convex  side  of  or 
entirely  filling  the  cell ; generally  with  a single  pyrenoid. 

Reproduction  by  the  division  of  any  cell  to  form  four  or  eight  auto- 
spores that  are  liberated  by  a rupture  of  the  old  mother  cell  wall  but 
remain  within  the  gelatinous  envelope  of  the  colony. 


■^WISCONSIN  PHYTOPLANKTON 


141 


KEY  TO  THE  SPECIES. 


Cells  lunate  to  sickle-shaped. 

Ends  of  cells  pointed K.  Lunaris 

Ends  of  cells  rounded K.  Obesa 

Cells  arcuate,  spiral,  or  vermiform  cylinders. 

Breadth  of  cells  2 /a  or  less K.  Contorta 

Breadth  of.  cells  over  2 /a K.  Elongata 


Kirchneriella  lunaris  (Kirchner)  Mobius.  PL  34,  Fig.  4. 

Abh.  d.  Senckenb.  Naturf.  Ges.  18:  331.  1894;  Chodat,  Mater,  pour  la  fl.  crypt. 

Suisse  1®:  202,  figs.  12r-12V.  1902. 

Cells  flattened,  crescent-shaped,  with  apices  some  distance  apart, 
about  twice  as  long  as  broad,  ends  tapering  to  a blunt  point;  irregu- 
larly arranged  in  groups  of  four  to  eight  within  the  gelatinous  colonial 
envelope.  Chloroplast  single,  filling  the  entire  cell  with  the  exception 
of  a small  part  on  the  concave  side;  pyrenoid  single.  (Facultative 
Planktont) . 

Cells  3-8  fji  broad,  6-15  /a  long ; colonies  up  to  250  fx  in  diam. 

Bear  (3)  (rr),  Beaverdam  (rr),  Birch  Island  (rrr),  Blake  (rr).  Chain  (ss), 
Chetek  (rr),  Cochrane  (rr).  Crab  (rrr).  Deer  (rr),  Devils  (2)  (rr).  Duck 
(rr),  Dummy  (sss),  Elizabeth  (rr).  Green  (2)  (rr).  High  (rr),  Hillman  (r), 
Horseshoe  (1)  (rr),  Jag  (rr),  Lindy  (rrr).  Little  Crooked  (rrr).  Little  Doc- 
tor (rr).  Long  (3)  (rrr).  Loveless  (rr).  Lower  Turtle  (rrr).  Lynx  (rrr),  Men- 
dota  (rr),  Meta  (rr).  Mud  (2)  (rr),  Nancy  (sss).  North  Twin  (rrr).  Paddock 
(rr),  Pardee  (rr).  Pine  Tree  (rr),  Pokegama  (1)  (r),  Pokegama  (3)  (sss), 
Poplar  (rr).  Prairie  (sss).  Round  (3)  (rrr),  St.  Croix  (r).  Shell  (r).  Spirit 
(rrr).  Squirrel  (rr).  Upper  Turtle  (rrr).  White  Ash  (rr). 

The  species  differ  from  K.- obesa  in  the  pointed  ends  of  the  cells.  The 
two  are  widely  distributed  plankton  organisms  but  have  never  been 
found  in  quantity  in  any  lake  of  the  state. 


var.  Dianae  Bohlin.  PL  34,  Fig.  5. 

Bih.  Kgl.  Sv.‘Vet.-Ak.  Handl.  23,  Afd.  3,  No.  7:  20,  pi.  1,  figs.  28-30.  1897. 

Cells  curved  until  the  apices  are  almost  touching,  apices  more  pointed 
and  frequently  slightly  twisted.  (Facultative  Planktont). 

Cells  3-5  fl  broad,  10-21  fi  long. 

Hillman  (rr).  Pine  (2)  (rr).  White  Ash  (r). 

The  cell  shape  of  this  variety  resembles  that  of  Selenastrum  but  the 
colony  differs  in  being  enclosed  by  a gelatinous  envelope.  The  apices 
are  much  sharper  than  in  the  typical  form. 


142 


WISCONSIN  PHYTOPLANKTON 


var.  irregularis  var.  nov.  PI.  35,  Fig.  1. 

Apices  of  cells  twisted  and  frequently  not  pointing  in  the  same  direc- 
tion. (Facultative  Planktont). 

Cells  4r-6  broad,  6-13  fi  long. 

Cochrane  (rr),  Pokegama  (1)  (r),  Tenderfoot  (rr). 

Although  the  cell  apices  of  K.  lunaris  var.  dianae  are  sometimes  not 
in  the  same  plane,  they  never  exhibit  the  twisting  found  in  this  variety. 
The  twisting  of  the  cells  of  this  variety  is  similar  to  that  of  K.  contorta 
but  they  have  the  shape  and  pointed  ends  that  characterize  K,  lunaris. 

Kirchneriella  obesa  (W.  West)  Schmidle.  PI.  35,  Figs.  2-3. 

Ber.  d.  Naturf.  Ges.  zu  Freiburg  i.  B.  7:  16  (83).  1893;  G.  S.  West,  Brit. 

Freshw.  Algae  226,  figs.  96a-96e.  1904. 

Cells  flattened  with  outer  side  markedly  convex  and  inner  sides 
parallel,  ends  rounded  and  tapering  slightly.  Chloroplast  single,  fill- 
ing the  entire  cell  with  the  exception  of  a small  portion  on  the  con- 
cave side;  with  one  pyrenoid.  (Facultative  Planktont). 

Cells  3-8  broad,  6-16  fx  long. 

Bear  (2)  (rr).  Bear  Trap  (rr).  Camp  (rr),  Catherine  (rr),  Center  (r). 
Chain  (rr),  Chetac  (r).  Crawling  Stone  (rrr).  Devils  (1)  (rrr),  Hillman  (rr), 
Kitten  (rr).  Lac  Court  Oreilles  (ss),  Lac  du  Flambeau  (rr),  Mendota  (r). 
Palmer  (rrr).  Pine  Tree  (rr),  Pokegama  (2)  (rr).  Poor  Farm  (rr).  Reserve 
(rr).  Rice  (1)  (rr).  Rock  (rrr).  Sand  (4)  (rr).  South  Turtle  (rr).  White- 
fish  (rrr).  Wildcat  (rr),  Winnebago  (rr). 

The  cells  of  this  species  might  be  described  as  thick  discs  incised  a 
third  to  a half  the  width  of  the  cell  did  not  other  members  of  the  genus 
show  that  this  effect  is  produced  by  a curving  of  the  cell. 

var.  MAJOR  (Bernard)  G.  M.  Smith.  PI.  35,  Fig.  4. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  636,  pi.  10,  fig.  7.  1918. 

Inner  face  between  cell  apices  curved;  apices  not  close  together, 
rounded  and  slightly  tapering.  (Facultative  Planktont). 

Cells  3-5  fi  broad,  8-21  /x  long. 

Carson  (rr).  Lac  Court  Oreilles  (r).  Wolf  (rr). 

This  variety  has  a large  open  space  between  the  apices  whereas  in 
the  typical  form  this  space  is  narrow  and  with  parallel  sides.  The  cells 
are  also  much  narrower  in  proportion  to  their  length.  Brunnthaler 
(in  Pascher,  Siisswasserfl.  Deutschl.  Osterr.  u.  d.  Schw.  5^:  180.  1915) 

has  placed  the  alga  as  a form  of  K.  lunaris  var.  dianae  but  the  cell  apices 
are  too  rounded  to  consider  it  a variety  of  K.  luTiaris. 


WISCONSIN  PHYTOPLANKTON 


143 


Yar.  APERTA  (Teiling)  Briinntlialer.  PI.  35,  Figs.  5-6. 

in  Pascher,  Siisswasserfl.  Deutschl.  osterr.  u.  d.  Schw.  5^:  182,  iig,  268.  1915. 

Kirchneriella  aperta  Teiling,  Sv.  Bot.  Tids.  6;  276,  fig.  9.  1912. 

Cells  with  blunt,  rounded  apices,  concave  side  between  apices  broadly 
V-sbaped.  (Facultative  Planktont). 

Diam.  cells  6-12  fx. 

Diamond  (rr),  Palmer  (ss). 

Kirchneriella  contorta  (Schmidle)  Bohlin.  PI.  35,  Fig.  7. 

Bih.  Kgl.  Sv.  Vet.-Ak.  Handl.  23,  Afd.  3,  No.  7:  20.  1897. 

Kirchneriella  obesa  var.  contorta  Schmidle,  Flora  78:  44,  pi.  7,  fig.  2.  1894. 

Cells  cylindrical,  arcuate  or  in  spirals  that  never  make  more  than 
iy2  turns;  ends  rounded,  not  tapering.  Cells  generally  lying  some 
distance  from  one  another  within  the  homogeneous  colonial  envelope. 
Chloroplast  single,  filling  the  entire  cell,  without  a pyrenoid.  Cells 
sometimes  spirally  arranged  in  the  colony;  rarely  more  than  sixteen 
cells  in  a colony.  (Facultative  Planktont). 

Cells  0.7-2.0  fi  broad,  8-14  /x  long ; colonies  up  to  60  ^ in  diam. 

Chain  (rrr),  Clear  (rr),  Cochrane  (rr),  Fowler  (rrr),  Mendota  (rrr),  Par- 
dee (rr),  Pine  Tree  (rrr).  Poor  Farm  (rrr). 

A species  which  at  first  glance  does  not  appear  related  to  K.  lunaris 
and  K.  obesa,  but  which  at  times  shows  a certain  resemblance  to 
K.  obesa  var.  major.  It  and  the  following  species  are  rare  algae  in 
Wisconsin.  They  are  closely  related,  the  chief  difference  being  the 
smaller  size  and  fewer  number  of  cells  in  the  colony  of  K.  contorta. 

Kirchneriella  elongata  G.  M.  Smith.  PI.  36,  Figs.  1-2. 

Bull.  Torr.  Bot.  Cl.  43  : 473,  pi.  24,  fig.  7.  1916. 

Cells  elongate-cylindrical  with  rounded  ends;  spirally  or  irregularly 
twisted.  Colonies  of  4-8-16  or  more  cells  arranged  in  a snarl  at  the 
center  of  a copious  homogeneous  gelatinous  sheath.  Chloroplast  single, 
parietal;  without  a pyrenoid.  (Facultative  Planktont). 

Cells  2-3  fx  broad,  15-25  fx  long ; colonies  up  to  100  fx  in  diam. 

Devils  (2)  (rrr).  Horse  (rrr),  Lac  Court  Orellles  (rr).  No  Mans  (rr). 
Palmer  (rr).  White  Ash  (sss). 

Sub-family  CRUCIGENIEAE. 

Cells  acicular,  fusiform,  ovoid,  triangular,  or  trapezoidal;  in  fiat 
eoenobia  with  the  number  of  cells  always  a multiple  of  two.  Cells 
quadrately  arranged  in  coenobe  or  in  a linear  series.  Coenobe  gener- 
ally without  a gelatinous  envelope.  Chloroplasts  1-4,  parietal,  disci- 
form or  laminate ; generally  with  one  pyrenoid. 


144 


WISCONSIN  PHYTOPLANKTON 


KEY  TO  THE  GENERA. 

Cells  quadrately  arranged. 

Quadrate  arrangement  apparent  in  front  view  of  cells. 


Outer  face  of  cells  without  spines Crucigenia 

Outer  face  of  cells  with  spines Tetrastrum 

Quadrate  arrangement  apparent  in  end  view  of  cells Tetradesmus 

Cells  arranged  in  a linear  series Scenedesmus 


CRUCIGENIA  Morren  1830. 

Coenobe  free-swimming,  of  four  cells  quadrately  arranged  with  a 
quadrangular  open  space  at  the  center  and  frequently  connected  to 
other  eoenobia  by  a gelatinous  envelope  or  the  remains  of  the  old  mother 
cell  walls.  Multiple  eoenobia  forming  a flat  plate  one  cell  in  thickness 
and  containing  4,  16,  32,  64  or  more  cells.  Cells  flattened;  ovoid,  tri- 
angular, trapezoidal,  or  semicircular  in  front  view ; with  a smooth  cell 
wall.  Chloroplasts  1-4,  parietal,  disciform  to  laminate,  with  or  with- 
out pyrenoids. 

Reproduction  by  autocolony  formation,  the  four  cells  of  the  coenobe 
generally  producing  autocolonies  at  the  same  time. 


KEY  TO  THE  SPECIES. 


Cells  apiculate C.  Apiculatum 

Cells  not  apiculate. 

Coenobe  with  a large  rectangular  open  space  at  the  center. 


Front  view  of  cells  trapezoidal C.  Fenestrata 

Front  view  of  cells  semicircular C.  Lauterbornei 

Coenobe  with  a small  open  space  at  the  center. 

Length  of  coenobe  greater  than  the  breadth. 

Wall  of  cell  the  same  thickness  throughout. 

Outer  face  of  cells  concave C.  Cruciata 

Outer  face  of  cells  convex. 

Cells  of  coenobe  regularly  arranged C.  Rectangularis 

Cells  of  coenobe  irregularly  arranged C.  Irregularis 

Wall  of  cell  thicker  at  the  poles C.  Truncata 

Length  of  coenobe  the  same  as  the  breadth. 

Cells  triangular,  with  fairly  acute  corners C.  Tetrapedia 

Cells  spherical  to  triangular,  with  rounded  corners C.  Quadrata 


Crucigenia  rectangularis  (Nageli)  Gay.  PI.  36,  Fig.  3. 

Recherches  sur  le.  dev.  et  la  class,  de  quelques  algues  vertes  100,  pi.  15,  fig.  151. 
1891. 

Coenobe  four-celled,  cells  in  mutual  contact  at  the  poles  and  sides 
and  with  a small  rectangular  open  space  at  the  center.  Generally 
united  in  compound  eoenobia  containing  an  indefinite  number  of  coen- 


WISCONSIN  PHYTOPLANKTON 


145 


obes.  Cells  ovoid  to  elongate-ovoid,  with  1-4  parietal,  disciform  chloro- 
plasts,  each  with  a single  pyrenoid.  Old  mother  cell  wall  frequently 
enclosing  young  coenobia  for  some  time.  (Facultative  Planktont). 

Cells  4r-7  /X  broad,  5-10  /x  long. 

Bear  (2)  (rr),  Beaverdam  (rr),  Big  (rrr),  Birch  Island  (rrr),  Devils  (1) 
(r),  Fowler  (rrr),  Half  Moon  (rr),  Hillman  (rr),  Kegonsa  (rr).  Lac  Court 
Oreilles  (rr),  Lindy  (rr).  Little  Bass  (2)  (rr).  Little  Doctor  (rr).  Mill  (rrr), 
Nancy  (rr),  Nicaboyne  (rr),  Okauchee  (rrr).  Old  Taylors  (rr).  Pine  Tree 
(rr).  Sand  (1)  (rr).  Upper  Nashotah  (rrr),  Winnebago  (rr). 

Crucigenia  irregularis  Wille.  PI.  36,  Figs.  4-5. 

Biol.  Cent.  18:  302.  1898;  Nyt.  Mag.  f.  Naturvidensk.  88:  10,  pZ.  1,  -fig.  15, 
1900;  W.  & G.  S.  West  Trans.  & Proc.  Bot.  Soc.  Edinburgh  23:  29,  pi.  1,  iig$. 
6-7.  1905. 

Coenobia  four-celled,  with  cells  in  contact  at  sides  and  poles,  at  other 
limes  without  a definite  arrangement.  Coenobia  irregularly  combined 
into  multiple  coenobia.  Cells  ovoid ; with  1-4  parietal,  disciform  chloro- 
plasts;  with  or  without  pyrenoids.  (Facultative  Planktont). 

Cells  4-9  /X  broad,  6-14  /x  long.  Coenobia  8-14  «,  broad,  15-30  /x  long. 

Browns  (rr).  Camp  (rr).  Fish  (rr).  Horseshoe  (2)  (rr),  Mudhen  (rr). 
Reserve  (rr),  Sand  (3)  (sss). 

The  cell  shape  is  quite  similar  to  that  of  C.  rectangularis  but  the  ar- 
rangement of  cells  within  the  coenobe  is  very  irregular  in  about  half 
the  colonies  one  meets  with.  This  irregular  cellular  arrangement  coup- 
led with  the  larger  cell  size  warrants  the  separation  of  the  alga  from 
C.  rectangularis.  The  alga  is  generally  reported  to  be  without  pyre- 
noids but  I have  frequently  found  them  in  the  chloroplasts  of  C.  irregu- 
laris. 

Crucigenia  crucifera  (Wolle)  Collins.  PI.  36,  Fig.  6. 

Tufts,  coll,  studies  2:  170.  1909. 

Staurogenia  crucifera  Wolle,  Bull.  Torr.  Bot.  Cl.  6:  140.  1877. 

Staurogenia  cruciatum  Wolle,  Freshw.  Algae  of  U.  S.  171,  pi.  157,  figs.  9-11. 
1887. 

Coenobia  four-celled,  rhomboidal,  with  rounded  ends,  slightly  con- 
cave sides,  and  a small  rectangular  open  space  at  the  center.  Cells 
elongate,  outer  face  concave,  inner  and  those  in  contact  with  other  cells 
straight.  Chloroplast  single,  parietal,  laminate;  without  a pyrenoid. 
(Facultative  Planktont). 

Cells  3.5-5  /X  broad,  5-7  /x  long.  Coenobia  9-11  /x  broad,  14^16  fx  long. 

Hillman  (rr).  Tenderfoot  (rr). 

The  arrangement  of  the  individual  coenobia  into  compound  coenobia 
is  generally  that  which  Wolle  gives  in  his  figure  9 of  Staurogenia  cruci- 


10 


146 


WISCONSIN  PHYTOPLANKTON 


atum.  Collin’s  surmise  that  the  reported  cruciform  marking  of  the 
cell  wall  is  probably  due  to  a division  of  the  cell  contents  is  correct  and 
what  Wolle  calls  the  cell  is  in  reality  the  coenobe.  The  remains  of  the 
old  cell  walls  play  an  important  part  in  binding  together  the  various 
coenobia  of  the  multiple  coenobe. 

Crucigenia  truncata  sp.  nov.  PI.  36,  Figs.  7-9. 

Coenobe  four-celled,  with  a small  rectangular  space  at  the  center  and 
held  in  compound  coenobia  of  indefinite  size  by  the  remains  of  old 
mother  cell  walls.  Cells  quadrately  arranged  with  bases  and  middle 
third  of  inner  sides  in  mutual  contact  but  with  apices  and  outer  faces 
free.  Cells  elongate,  ovoid,  with  free  ends  truncate.  Cell  wall  at  free 
apex  thicker  than  in  other  parts.  Chloroplasts  1-4,  parietal,  disci- 
form, without  pyrenoids.  ( Euplanktont ) . 

Cells  4-6  fi  broad,  6-10  fi  long.  Coenobia  6-12  broad,  12-20 
fi  long.  Compound  coenobia  up  to  50x75  fi. 

Chain  (rr),  Hillman  (rr),  Pine  Tree  (rr),  Travis  (rr). 

The  species  is  differentiated  by  its  flattened  cell  apices  and  the  thicker 
walls  at  the  apices.  The  cells  are  always  regularly  arranged  within  the 
coenobe,  but  when  in  compound  coenobia  the  arrangement  is  frequently 
irregular. 

Crucigenia  apiculata  (Lemmermann)  Schmidle.  PI.  37,  Fig.  1. 
Allg.  Bot.  Zeitschr.  6:  234.  1900. 

Staurogenia  apiculata  Lemmermann,  Bot.  Cent.  76:  151.  18'98;  For- 

Bchungsbr.  a.  d.  Biol.  Stat.  zu  Plon  7:  119,  pi.  1,  fig.  14.  1899;  Snow,  Bull. 
U.  S.  Fish  Comm.  22:  376,  pi.  1,  figs.  V^V«.  1903. 

Tetrastrum  apiculatum  (Lemmermann)  Brunnthaler,  in  Pascher,  Siisswas- 
serfl.  Deutschl.,  Osterr.  u.  d.  Schw.  5^:  177,  fig.  258.  1915;  G.  M.  Smith,  Bull. 
Torr.  Bot.  Cl.  43  : 472,  pi.  24,  fig.  3.  1916. 

Coenobia  four-celled,  embedded  in  a delicate  gelatinous  sheath.  Cells 
quadrately  arranged  with  their  long  axes  parallel  and  a small  rectangu- 
lar space  at  the  center.  Coenobia  generally  in  multiple  coenobia  which, 
when  containing  large  numbers  of  coenobia,  are  frequently  irregular. 
Cells  ovoid  to  triangular,  with  a short  conical  projection  at  the  free 
apex  and  frequently  another  one  at  the  side  of  the  base  away  from  the 
center  of  the  coenobe.  Each  cell  containing  1-4  parietal  disciform 
chloroplasts  with  one  pyrenoid.  (Euplanktont). 

Cells  3-7  /A  broad,  5-10  fi  long.  Coenobia  6-12.5  fx  broad,  9-18 
/i  long.  Compound  coenobia  up  to  150  p,  broad. 

Mendota  (rrr).  Palmer  (rrr),  South  Crab  (rr). 

The  cells  of  16-celled  multiple  coenobia  are  regularly  arranged  but 
when  multiple  coenobia  contain  150-200  cells  the  arrangement  is  fre- 


WISCONSIN  PHYTOPLANKTON 


147 


quently  irregular.  The  gelatinous  sheath  enclosing  the  colony  is  very 
delicate  and  can  only  be  seen  when  properly  stained.  This  species  was 
placed  in  the  genus  Tetrastrum  in  a preliminary  list,  but  it  is  more 
closely  related  to  Crucigenia  than  to  Tetrastrum. 

Crucigenia  quadrata  Morren.  PI.  36,  Figs.  10-14. 

Ann.  Sci.  Nat.  20:  415,  pi.  15,  figs.  1-5.  1830. 

Staurogenia  triangularis  Chodat,  Mem.  Herb.  Boiss.  1,  No.  17 : 7,  figs.  14-19. 
1900. 

Crucigenia  triangularis  (Chodat)  Schmidle,  Allg.  Bot.  Zeitschr.  6:  234.  1900. 

Staurogenia  multiseta  var.  punctata  Schmidle,  Ber.  d.  D.  bot.  Ges.  18:  157, 
pi.  6,  figs.  13-14.  1900. 

Coenobia  four-celled,  circular  in  outline.  Cells  in  mutual  contact  at 
or  with  very  small  rectangular  openings  at  center  of  the  coenobe. 
Four  coenobia  compressed  to  form  rectangular  multiple  coenobia  which 
in  turn  are  joined  to  other  sixteen-celled  multiple  coenobia.  Cells 
spherical  to  triangular;  with  a smooth  wall  or  with  1-6  minute  knob- 
like projections  on  the  wall.  Chloroplasts  1-4,  parietal,  disciform,  with 
or  without  pyrenoids.  (Facultative  Planktont) . 

Cells  2.5-6  fL  broad,  3-7  p,  long.  Coenobia  5.5-17  /x  in  diam.  16- 
celled  compound  coenobia  12-30  /x  in  diam. 

Carson  (rrr).  Chain  (rr),  Hillman  (sss).  Kitten  (rrr),  Lac  du  Flambeau 
(rr).  Palmer  (sss),  Pardee  (rr).  Tenderfoot  (rrr).  White  Sand  (rrr). 

Pyrenoids  are  very  prominent  in  the  chloroplasts  of  certain  colonies 
while  other  colonies  collected  from  the  same  station  show  no  trace  of 
them.  In  some  of  the  colonies  from  Hillman  lake  small,  globular,  but- 
ton-like structures  were  observed  on  the  cell  walls.  Such  structures 
have  been  noted  by  Schmidle  and  form  the  distinctive  character  of  his 
variety  punctata  of  Staurogenia  multiseta  [Tetrastrum  multisetum 
(Schmidle)  Chodat].  If  the  variety  is  to  be  recognized  it  should  be 
called  C.  quadrata  var.  punctata  (Schmidle)  but  I am  of  the  opinion 
that  it  is  not  a sufficiently  constant  character  to  warrant  recognition. 
There  is  likewise  no  justification  for  considering  C.  triangularis  (Cho- 
dat) Schmidle  a distinct  species  since  it  does  not  differ  in  any  respect 
from  C.  quadrata. 

Crucigenia  tetrapedia  (Kirchner)  W.  & G.  S.  West.  PI.  37,  Fig.  2. 

Trans.  Roy.  Irish  Acad.  32,  Sec.  B:  62,  pi.  1,  figs.  11-12.  1902. 

Staurogenia  tetrapedia  Kirchner,  Jahreshefte  d.  Ver.  f.  Vaterl.  Naturk.  i. 
Wiirttemberg  1880,  pi.  2,  fig.  1. 

Tetrapedia  emarginata  Schroder,  Ber.  d.  D.  bot.  Ges.  15:  492,  pi.  25,  figs. 
6a-6c.  1897. 

Lemmermannia  emarginata  (Schroder)  Chodat,  Mem.  Herb.  Boiss.  1,  No. 
IT;  figs.  1-^.  1900. 


148 


WISCONSIN  PHYTOPLANKTON 


Lemmermannia  tetrapedia  (Kirchner)  Lemmermann,  Arkiv.  for  Botanik  2, 
No.  2:  157.  W04. 

Coenobia  four-celled,  with  a very  small  rectangular  open  space  at 
the  center.  Frequently  joined  in  multiple  coenobia  of  sixteen -cells  that 
may  be  connected  in  turn  to  other  16-celled  multiple  coenobia.  Cells 
flattened,  triangular,  with  rounded  corners.  Cell  contents  homogeneous, 
or  with  a single  parietal  chloroplast,  with  or  without  pyrenoids.  (Fac- 
ultative Planktont). 

Diam.  cells  4.8-9.5  /x;  diam.  coenobia  8-15  /x;  diam.  16-celled  multiple 
coenobia  up  to  40  /x. 

Palmer  (rr). 

Certain  investigators  have  noted  that  the  cell  contents  are  at  times 
absolutely  homogeneous.  This  has  caused  Schroder  to  consider  the  alga 
a species  of  Tetrapedia,  one  of  the  Myxophyceae,  but  the  Wests  have 
given  cogent  reasons  for  considering  it  a Crucigenia.  1 have  found  a 
distinct  parietal  chloroplast  and  pyrenoid  in  the  cells  whereas  Chodat 
states  that  there  is  a chloroplast  but  no  pyrenoid.  His  founding  of  the 
genus  Lemmermannm  upon  this  single  character  (lack  of  a pyrenoid) 
has  rightly  been  called  by  G.  S.  West  (Brit.  Freshw.  Algae  217.  1904) 
‘‘the  climax  of  absurdity.” 

Crucigenia  fenestrata  Schmidle.  PI.  37,  Fig.  3. 

Allg.  Bot.  Zeitschr.  6:  234.  1900. 

Staurogenia  fenestrata  Schmidle,  Allg.  Bot.  Zeitschr.  3:  107,  fig.  1.  1897. 

Coenobia  four-celled,  rectangular,  with  a medium-sized  opening  at 
tile  center;  with  an  inconspicuous  gelatinous  sheath.  Frequently  in 
multiple  coenobia  with  the  component  coenobia  lying  close  together. 
Cells  trapezoidal,  with  the  longest  face  at  the  outside  of  the  coenobe. 
Chloroplast  single,  except  just  before  division,  parietal,  without  a pyre- 
noid ( ? ) . ( Euplankt ont ) . 

Cells  3-5  fx  broad,  5-12  /x  long ; coenobia  8-14  /x  broad. 

Bettine  (rr).  White  Sand  (rr). 

The  specimens  that  I have  found  do  not  agree  in  all  respects  with 
Schmidle ’s  description  since  there  was  no  gelatinous  sheath  surround- 
ing the  coenobe  and  filling  the  central  space. 

Crucigenia  Lauterbornei  Schmidle.  PI.  37,  Fig.  4. 

Allg.  Bot.  Zeitschr.  6:  234.  1900. 

Staurogenia  Lauterbornei  Schmidle,  Allg.  Bot.  Zeitschr.  2:  192,  fig.  1.  1896. 

Coenobia  four-celled,  cells  in  contact  with  one  another  at  their  apices 
only  and  with  a large  square  open  space  at  the  center  of  the  coenobe. 


WISCONSIN  PHYTOPLANKTON 


149 


Coenobia  joined  in  multiple  coenobia  of  at  least  sixteen  cells  by  the  re- 
mains of  old  cell  walls  and  a gelatinous  envelope.  Cells  flattened,  sub- 
hemispherical  in  front  view  with  the  flattened  side  towards  the  center 
of  the  coenobe.  Chloroplast  single,  parietal,  on  the  outer  face  of  the 
cell;  with  one  pyrenoid.  (Euplanktont). 

Cells  4.5-9  fx  broad,  8-15  /x  long.  Coenobia  15-25  /x  in  diam ; multiple 
coenobia  up  to  150  fx  in  diam. 

Kegonsa  (r),  Fokegama  (rr),  Rice  (1)  (r),  Upper  Turtle  (r). 

A very  distinct  species  and  one  that  is  readily  recognized  by  the  large 
opening  at  the  center  of  the  colony.  C.  fenestrata  also  has  a large,  rec- 
tangular open  space  at  the  center  of  the  coenobe  but  the  two  species 
have  quite  differently  shaped  cells ; those  of  C,  Lauterhornei  being  semi- 
circular in  front  view,  and  those  of  C.  fenestrata  trapezoidal. 

TETKASTRUM  Chodat  1895. 

Coenobia  four-celled,  with  cells  cruciately  arranged  in  a flat  plate; 
at  times  embedded  in  a thin  gelatinous  envelope.  Cells  triangular  to 
ovoid,  with  several  spines  or  setae  on  the  free  face.  Chloroplasts  1-4, 
parietal,  disciform,  with  or  without  pyrenoids. 

Reproduction  by  autocolony  formation  in  any  cell. 

The  genus  is  closely  related  to  Crucigenia,  differing  only  in  the  spines 
on  the  margins  of  the  cells  and  an  absence  of  an  association  in  multiple 
coenobia. 

Tetrastrum  staurogeniaeforme  (Schroder)  Lemmermann.  PI.  37, 

Figs.  5-6. 

Ber.  d.  D.  bot.  Ges.  18:  95.  1900. 

Cohniella  Staurogeniaeformis  Schroder,  Ber.  d.  D.  bot.  Ges.  15:  373,  pZ.  17, 
ftg.  5.  1897. 

Coenobia  four-celled,  with  a very  minute  open  space  at  the  center 
of  the  colony.  Coenobe  embedded  in  a very  delicate  gelatinous  envelope. 
Cells  cruciately  arranged,  triangular,  with  5-6  very  delicate  setae  on 
the  free  surface.  Chloroplasts  1-4,  parietal,  disciform,  with  or  without 
pyrenoids.  ( Euplanktont) . 

Diam.  cells  (without  setae)  3-6  fx;  diam.  coenobia  (without  setae) 
7-15  /X.  Setae  4-8  fx  long. 

Horse  (rr),  Mendota  (rrr). 

The  setae  on  the  outer  face  of  the  cells  are  very  delicate  and  easily 
overlooked.  If  the  setae  are  not  taken  into  consideration  the  alga  looks 
exactly  like  Crucigenia  quadrat  a. 


150 


WISCONSIN  PHYTOPLANKTON 


TETRADESMUS  G.  M.  Smith  1913. 

Colonies  free-floating,  four-celled,  rarely  two-  or  three-celled.  Cells 
in  two  planes  with  two  cells  in  each  plane  and  joined  along  the  long 
axes  when  the  colony  is  viewed  from  the  side.  Viewed  from  the  top 
cells  quadrately  arranged.  Cells  elliptic-fusiform  to  broadly  elliptic, 
with  outwardly  divergent  or  straight  apices.  Chloroplast  single,  pari- 
etal and  laminate  or  completely  filling  the  cell ; pyrenoid  single,  central 
or  eccentric. 

Reproduction  by  autocolony  formation  in  any  cell  of  the  colony,  the 
young  coenobia  being  liberated  by  a rupture  of  the  mother  cell  wall. 

Tetradesmus  wisconsinensis  G.  M.  Smith.  PI.  37,  Figs.  7-11. 
Bull.  Torr.  Bot.  Cl.  40:  76,  pi.  1,  figs.  1-2,  3-20.  1913. 

Cells  elliptic-fusiform,  apices  attenuated  and  outwardly  divergent. 
Pyrenoids  eccentric.  (Facultative  Planktont). 

Cells  4^6  fji  broad,  12-14.5  fx  long. 

Blake  (rrr),  Mendota  (rr),  Nancy  (rrr). 

SCENEDESMUS  Meyen  1829. 

Coenobe  a flat  (rarely  curved)  plate  of  ellipsoidal,  ovoid,  or  acicular 
cells  with  cell  number  always  a multiple  of  two.  Cells  in  lateral  con- 
tact and  in  one  or  two  rows.  Cell  wall  smooth,  corrugated,  granulate, 
or  spicate ; with  or  without  marginal  or  lateral  teeth  or  spines.  Chloro- 
plast single,  parietal,  and  laminate  in  young  cells;  frequently  filling 
entire  cell  in  older  colonies ; pyrenoids  single,  central  or  eccentric. 

Reproduction  by  autocolonies  from  any  or  all  cells  of  the  coenobe, 
the  number  of  cells  in  the  colony  not  necessarily  the  same  as  that  of 
the  mother  colony. 


KEY  TO  THE  SPECIES. 

Walls  smooth,  without  granulations,  lateral  ridges,  terminal  teeth  or  spines. 


Cells  acicular  to  broadly  elliptic,  with  pointed  ends. 

Colony  a flat  plate. 

All  cells  in  colony  erect S.  Obliqutjs 

Median  cells  erect,  terminal  cells  lunate S.  Dimoephus 

Colony  a curved  or  twisted  plate. 

Cells  forming  a curved  surface S.  Acuminatus 

Cells  alternately  arranged  with  terminal  cells  not  in  the 

same  plane  as  the  others S.  Beenardu 

Cells  ovoid  to  cylindrical,  with  rounded  ends. 

Arrangement  of  cells  a single  linear  or  subalternating  but 

never  a double  series S.  Bijuoa 

Arrangement  of  cells  a double  linear  series S.  Arcuatus 


WISCONSIN  PHYTOPLANKTON 


151 


Wall  variously  sculptured  or  ridged,  at  times  with  terminal  teeth  or  spines. 


Longitudinal  ridges  on  sides  of  the  cells. 

Without  terminal  teeth  or  spines S.  Acutiformis 

With  terminal  teeth  or  spines. 

Terminal  cells  with  long  spines  at  poles S.  Aematus 

All  cells  with  short  teeth  at  poles S.  Brasiliensis 

Longitudinal  ridges  not  present  on  sides  of  the  cells. 

Teeth-like  spines  covering  entire  wall S.  Hystrix 

Teeth  or  spines  confined  to  poles,  outer  face  of  terminal 
cells,  or  middle  of  all  cells. 

Cells  with  short  teeth  at  poles S.  Denticulatus 

Cells  with  long  spines. 

Spines  on  both  median  and  terminal  cells. 

Poles  of  cells  only  region  bearing  spines. 

Cells  ovoid  to  ovoid-cylindrical S.  Longus 

Cells  naviculoid  S.  Opoliensis 

Poles  and  median  part  of  cells  bearing  spines S.  Abundans 

Spines  confined  to  terminal  cells. 

Cells  ovoid  to  ovoid-cylindrical S.  Qtjadricauda 

Cells  naviculoid  S.  Opoliensis 


SCENEDESMUS  OBLIQUES  (Turpin)  Kiitzing.  PI.  37,  Figs.  12-14. 
Linnaea  8:  609.  1833;  G.  S.  West,  Brit.  Freshw.  Algae  220,  fig.  92a.  1904. 

Cells  of  2-4-8  cells  arranged  in  a single  linear  or  sublinear  series. 
Cells  fusiform,  with  acute  apices ; interior  cells  with  straight  sides,  outer 
face  of  terminal  cells  slightly  concave,  straight,  or  convex.  Cell  wall 
smooth,  without  terminal  teeth  or  spines.  (Tychoplanktont). 

Cells  3-9  /X  broad,  10-21  /x  long.  4-celled  coenobia  10-21  /x  broad, 
12.5-24  fjL  long. 

Balsam  (rrr).  Bear  (1)  (rrr),  Blake  (rr).  Bone  (rr).  Grassy  (rr),  Hill- 
man (rrr).  Horseshoe  (2)  (rrr),  Lindy  (rr).  Little  Bear  (rrr).  Little  Doctor 
(rr).  Little  Rice  (2)  (rrr).  Loon  (rr),  Mendota  (rrr),  Pewaukee  (rrr).  Poor 
Farm  (rrr).  Pope  (rrr).  Rice  (2)  (rr).  Sand  (3)  (rrr).  Sand  (4)  (rrr).  Up- 
per Nemahbin  (rrr).  White  Ash  (rrr). 


ScENEDESMUS  DiMORPHUS  (Turpin)  Kiitzing.  PI.  37,  Figs.  15-17. 

Linnaea  8:  608.  1833;  G.  M.  Smith,  Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18' : 
434,  pi.  32,  figs.  185-189;  pi.  33,  figs.  190-195.  1916. 

Coenobia  of  four  or  eight  cells  arranged  in  a linear  or  alternating 
series.  Cells  fusiform  with  apices  attenuated  to  delicate  points.  In- 
terior cells  erect,  outer  erect  or  markedly  lunate.  Cell  wall  smooth, 
without  terminal  teeth  or  spines.  (Facultative  Planktont). 

Cells  2-5  /X  broad,  18-23  /x  long.  4-celled  coenobia  18-23  fx  broad, 
12-25  fx  long. 

Dunham  (rrr).  Horse  (r),  Pine  Tree  (sss),  Poor  Farm  (ss),  Travis  (sss). 


152 


WISCONSIN  PHYTOPLANKTON 


The  outwardly  turned  lunate  terminal  cells,  together  with  the  pro- 
nounced alternate  arrangement  distinguishes  this  species  from  the  fore- 
going. I have  given  elsewhere  (1.  c.)  the  reasons  for  considering  this 
a distinct  species  and  not  a variety  of  S.  obliquus, 

SCENEDESMUS  ACUMiNATus  (Lagorheim)  Chodat.  PI.  38,  Figs.  1-4. 

Mater,  pour  la  fl.  crypt.  Suisse  1":  211.  1902. 

Selenastrum  acuminatum  Lagerheim  dfvers.  Kgl.  Vet.-Ak.  Forh.  S9:  No.  2: 
71,  pi.  3,  figs.  27-30.  1882. 

Coenobia  curved,  of  4 or  8 (generally  4)  cells.  All  of  the  cells  of  a 
colony  arcuate  or  lunate,  fusiform,  with  the  ends  gradually  tapering 
to  a fine  point.  Cell  wall  smooth,  without  teeth,  granulations  or  spines. 
(Facultative  Planktont). 

Cells  3-7  fjL  broad,  30-40  fi  between  apices. 

Horse  (sss). 

This  species  should  not  be  confused  with  Selenastrum  acuminatus 
G.  S.  West  non  Lagerheim,  a species  which  I have  already  discussed 
in  connection  with  Selenastrum  Westii  G.  M.  Smith. 

ScENEDESMUS  Bernardii  G.  M.  Smith.  PI.  38,  Figs.  5-9. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18^:  436,  pi.  33,  figs.  196-208.  1916. 

Colonies  of  2-4-8  cells.  Interior  ceils  fusiform,  lunate  or  sigmoid, 
with  acute  apices;  alternately  arranged  with  apices  in  contact  with 
apices  or  median  portion  of  adja.cent  cells.  Terminal  cells  fusiform  to 
lunate,  frequently  at  an  angle  to  the  plane  of  the  coenobe,  in  contact 
Avith  the  interior  cells  by  the  apex  only.  Cell  wall  smooth,  without 
terminal  spines  or  teeth.  ( Tychoplanktont  ?). 

Cells  3-6  fl  broad,  8-17  /x  long. 

Monona  (rrr). 

ScENEDESMUS  BiJUGA  (Turpin)  Lagerheim.  PI.  37,  Pigs.  18-20. 
Nuova  Notarisia  1893:  158.  1893. 

Scenedesmus  hijugatus  (Turpin)  Kiitzing.  G.  S.  West,  Brit.  Freshw.  Algae 
220,  fig.  92c.  1904. 

Coenobes  flat,  of  2^r-8  cells  in  a single  (rarely  subalternate)  series. 
Cells  oblong-elliptic  to  ovoid,  with  broadly  rounded  ends.  Cell  wall 
smooth,  Avithout  teeth  or  spines.  (Tychoplanktont). 

Cells  4-7  fl  broad,  7-18  fi  long.  4-celled  colonies  7-18  fi  broad,  16-25 
fl  long. 

Fowler  (rrr),  Lindy  (rr),  Little  Bice  (2)  (rr).  Mill  (rr).  Poplar  (rrr), 
Silver  (2)  (rr),  Streitor  (rr).  Upper  Turtle  (rrr).  Wolf  (rr). 


WISCONSIN  PHYTOPLANKTON 


153 


var.  ALTERNANs  (Reinsch)  Borge.  PI.  38,  Figs.  10-11. 

Ai-kiv.  for  Botanik  6,  No.  1:  57.  1906. 

Scenedesmus  alternans  Reinsch,  Abh.  Senckenb.  Naturf.  Ges.  6:  135,  pi.  20, 
ng.  D‘.  1866. 

Colonies  flat,  generally  8-celled,  with  a very  marked  alternate  ar- 
rangement of  the  component  cells.  Cells  ovoid  to  elliptic.  (Tycho- 
planktont). 

Cells  4-8  fjL  broad,  6-15  /x  long.  8-celled  coenobia  12-30  /x  broad, 
22^5  /X  long. 

Blake  (rr).  Devils  (1)  (rrr),  Muskallonge  (rr). 

Since  cultural  studies  have  shown  that  the  alternate  arrangement  of 
cells  is  a constant  character  it  is  proper  to  consider  this  a distinct  vari- 
ety. The  variety  has  also  been  found  in  lakes  where  the  typical  form 
is  absent. 

Scenedesmus  arcuatus  Lemmermann.  PI.  38,  Figs.  12-14. 
Forscbungsbr.  a.  d.  Biol.  Stat.  zu  Plon  7:  112,  pi.  1,  figs.  2-4.  1899. 

Colonies  always  curved,  of  4r-8-16  (generally  8)  cells  arranged  in  a 
double  row.  Cells  ovoid,  sometimes  angular  by  mutual  compression 
at  the  base.  -Coenobia  with  small  interstices  between  the  cells.  Cell 
wall  smooth,  without  spines  or  teeth.  (Euplanktont). 

Cells  3-9  /X  broad,  9-17  /x  long.  8-celled  coenobia  15-25  /x  broad, 
15-40  /X  long. 

Beaverdam  (rr),  Blake  (rrr),  Camp  (rrr).  Center  (ss).  Chain  (rr), 
Cochrane  (rr),  Cranberry  (rr),  Hillman  (r).  Lac  Court  Oreilles  (rr).  Lac  du 
Flambeau  (rr).  Little  Bass  (2)  (rr).  Little  Crooked  (rr).  Long  (1)  (rrr). 
Long  (3)  (rr).  Lower  Turtle  (rr),  Mendota  (sss),  Meta  (rrr).  North  Turtle 
(rr),  Owen  (rrr).  Paddock  (rrr).  Palmer  (rrr),  Pardee  (rr),  Pokegama  (2) 
(rr).  Reserve  (rr).  Round  (1)  (rrr).  Sand  (1)  (rrr).  Sand  (4)  (rrr).  Shell 
(rrr),  Sishebogema  (rr).  Tied  Canoe  (rr).  Upper  Turtle  (rr).  Wolf  (r). 

One  of  the  few  species  of  the  genus  that  is  exclusively  confined  to 
the  plankton.  The  curving  of  the  coenobe  and  the  double  series  of 
ovoid  cells  at  once  separates  it  from  all  other  species. 

var.  CAPiTATUS  G.  M.  Smith.  PI.  38,  Figs.  15-16. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  637,  pi.  11,  figs.  4-5.  1918. 

Cells  with  nodular  thickenings  at  the  poles.  (Euplanktont). 

Cells  5-11  /X  broad,  11-23  /x  long.  8-eelled  colonies  22-27  /x  broad, 
20-35  /X  long. 


Center  (rr). 


154 


WISCONSIN  PHYTOPLANKTON 


var.  PLATYDISCA  G.  M.  Smith.  PL  39,  Figs.  1-3. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18*:  451,  pZ.  30,  figs.  101-105.  1916. 

Colonies  always  flat,  generally  8-celled.  Cells  oblong-elliptic  and 
arranged  in  a double  series.  Coenobia  with  small  interstices  between 
the  cells.  (Facultative  Planktont). 

Cells  4.5-T.5  ix  broad,  8-17  fx  long.  8-celled  coenobia  11-30  fx  broad, 
18-30  [X  long. 

Camp  (rrr).  Eagle  (rr),  Fowler  (rr),  George  (rr).  Horse  (rrr),  Kegonsa 
(ss).  Paddock  (rr).  Pine  (1)  (rr). 

An  alga  that  has  been  considered  a normal  variation  of  S.  hijuga  but 
one  which,  as  stated  elsewhere  (1.  c.),  seems  more  closely  related  to 
S.  arcxmtus. 

ScENEDESMus  ACUTiFORMis  Schroder.  PL  39,  Figs.  4-6. 
Forschungsbr.  a.  d.  Biol.  Stat.  zu  Plon  5:  45,  pZ.  2,  figs.  4a-4b.  1897. 

Coenobia  flat,  of  2-4-8  (generally  4)  cells  arranged  in  a linear  series. 
Cells  fusiform,  with  acute  apices.  Cell  wall  of  interior  cells  with  a 
single  ridge  that  extends  from  pole  to  pole  on  each  side ; wall  of  termi- 
nal cell  with  2-4  ridges.  Poles  of  cells  without  spines  or  teeth.  (Fac- 
ultative Planktont). 

Cells  5-8  ix  broad,  16-22  fx  long.  4-celled  colonies  16-22  fx  broad, 
20-25  fx  long. 

Mendota  (rr).  Rice  (1)  (rrr). 

Only  a single  longitudinal  ridge  can  be  seen  in  a front  view  of  the 
cell  but  the  number  of  ridges  is  readily  ascertained  in  an  end  view  of 
cells.  The  presence  of  these  ridges  without  accompanying  spines  or 
teeth  separates  this  from  other  species. 

ScENEDESMUs  ARMATUS  (Chodat)  G.  M.  Smith.  PL  39,  Figs.  7-10. 
Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18*:  460,  pi.  29,  figs.  90-93.  1916. 

Coenobia  of  2-4^8  cells  arranged  in  a linear  or  subalternating  series. 
Cells  ovoid  to  oblong-ellipsoid;  with  rounded  apices.  Terminal  cells 
with  a single  long  spine  at  each  pole.  Both  sides  of  cells  with  a longi- 
tudinal ridge  that  may  extend  from  pole  to  pole  but  is  generally  indis- 
tinct in  the  median  portion  of  the  cell.  (Facultative  Planktont). 

Cells  4-7  fx  broad,  7-16  fx  long.  4-celled  coenobia  (without  spines) 
7-16  fx  broad,  16-25  fx  long.  Spines  5-7  /a  long. 

Bear  (2)  (rr).  Bear  Trap  (rrr).  Bone  (rr).  Browns  (rr),  Carson  (rr).  Fish- 
trap  (rrr).  Horseshoe  (2)  (rr).  Lac  Court  Oreilles  (rr).  Little  Butternut  (rrr), 
Little  Crooked  (rr).  Loveless  (rr).  Lynx  (rrr),  Mendota  (rrr),  Pardee  (rrr). 
Pine  Tree  (rr),  St.  Croix  (rrr),  Silver  (rr).  Upper  Turtle  (rrr).  Wolf  (rr). 


WISCONSIN  PHYTOPLANKTON 


155 


var.  major  var.  nov.  PI.  39,  fig.  11. 

Cells  up  to  9 broad  and  25  /i  long.  Spines  15  long.  (Facultative 
Planktont  ?). 

Palmer  (rr). 

ScENEDESMUS  BRASiLiENSis  Bohlin.  PI.  39,  Figs.  12-14. 

Bill.  Kgl.  Sv.  Vet.-Ak.  Handl.  23,  Afd.  3,  No.  7:  22,  pi.  1,  figs.  36-37.  1897. 

Coenobia  flat,  of  2^:-8  (generally  4)  cells  arranged  in  a single  linear 
series.  Cells  cylindrical  to  ovoid-ellipsoid,  with  a single  longitudinal 
ridge  extending  from  pole  to  pole  on  each  side  of  the  cell.  Poles  with 
1-4  small  teeth.  (Facultative  Planktont). 

Cells  3-6  fi  broad,  11-24  fi  long.  4-celled  coenobia  11-24  p.  broad, 
12-25  long. 

Bear  (2)  (r),  Beaverdam  (rrr),  Chain  (rrr),  Clare  (rrr),  Deer  (rrr),  Jag 
(rr),  Lac  du  Flambeau  (rrr).  Lake  of  the  Woods  (rrr),  Lindy  (rr).  Little 
Doctor  (rr).  Old  Taylors  (rr).  Pine  (2)  (rr).  Rice  (1)  (rr).  White  Sand  (rrr). 

The  species  may  be  distinguished  from  S.  denticuLatus  by  the  linear 
ridges  on  the  sides  of  the  cells. 

ScENEDESMUS  HYSTRix  Lagerheim.  PI.  39,  Figs.  15-16. 
dfvers.  Kgl.  Vet.-Ak.  Porh.  39,  No.  2:  62,  pi.  2,  fig.  18.  1882. 

Coenobia  flat,  of  2-4^8  cells  joined  in  a single  linear  series.  Cells 
oblong-cylindrical,  with  blunt  conical  apices.  Entire  surface  of  cells 
covered  with  minute  spines.  (Tychoplanktont). 

Cells  3-5  IX  broad,  8-18  [x  long.  4-celled  coenobia  8-18  fx  broad,  12- 
25  fx  long. 

Rudolph  (rrr). 

ScENEDESMUS  DENTICULATUS  Lagerheim.  PI.  39,  Figs.  17-19. 
Ofvers.  Kgl.  Vet.-Ak.  Forh.  39,  No.  2:  61,  pi.  2,  figs.  13-17.  1882. 

Coenobia  flat,  generally  four-celled.  Cells  ovoid  to  ovoid-ellipsoid, 
arranged  in  a linear  or  subalternating  series.  Poles  of  cells  without 
ridges  but  with  1-4  short  spines.  (Facultative  Planktont). 

Cells  5-11  fx  broad,  7-15  fx  long.  4-celled  coenobia  7-15  fx  broad, 
15-22  fx  long. 

Amicoy  (rr).  Bear  (2)  (rr).  Browns  (rr).  Chain  (rr).  Deer  (rrr).  High  (r), 
Hillman  (rr).  Horse  (rrr).  Horseshoe  (2)  (rr).  Lac  du  Flambeau  (rrr),  Lit- 
tle Doctor  (rrr).  Silver  (3)  (rr).  White  Ash  (rr).  Wolf  (rr). 


156 


WISCONSIN  PHYTOPLANKTON 


ScENEDESMUs  LONGUS  Meyen.  PI.  39,  Figs.  20-22. 

Nova  Acta  Phys.-Med.  Acad.  Caes.  Leop.  Nat.  Cur.  14:  774,  pi.  43,  fig.  28. 
1829.  G.  M.  Smith,  Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  469,  pi.  31,  figs. 
156-158.  1916. 

Scenedesmus  quadricauda  var.  setosus  (Kirchner)  Lagerheim,  5fvers.  Kgl. 
Sv  Vet.-Ak.  Forh.  39,  No.  2:  63.  1882. 

Coenobe  flat,  of  2-4-8  (generally  4)  cells  arranged  in  a single  linear 
series.  Cells  ovoid  to  oblong-cylindrical,  with  rounded  poles.  Poles 
of  all  cells  with  1-2  spines.  Cell  wall  destitute  of  spines  except  at  the 
poles.  ( Tychoplanktont) . 

Cells  4-5  fi  broad,  8-11  long.  4-celled  coenobia  8-11  fx  broad,  16- 
20  jx  long. 

Rock  (rr). 

var.  Naegelii  (Brebisson)  comb.  nov.  PL  40,  Figs.  1-2. 

Scenedesmus  Naegelii  de  Brebisson,  Mem.  de  la  soc.  Imp.  de  Sc.  Nat.  de 
Cherbourg  4:  158.  1856. 

Scenedesmus  eaudatus  Nageli  non  Corda,  Gatt.  einz.  Algen  91,  pi.  5,  figs. 
2c-2d.  1849. 

Colonies  flat,  always  eight-celled.  Cells  cylindrical,  with  rounded 
poles.  Terminal  cells  with  spines  at  both  poles,  interior  cells  with 
spines  at  one  pole,  rarely  at  both  poles.  (Facultative  Planktont). 

Cells  6.6-11  /X  broad,  18-33  /x  long.  8-celled  colonies  18-33  /x  broad, 
50-85  /X  long. 

Blake  (rr).  Camp  (rrr).  Poor  Farm  (rrr).  White  Ash  (rr). 

This  alga  was  described  by  de  Brebisson  from  the  drawings  of 
/S».  quadricauda  by  Nageli.  In  my  monograph  of  Scenedesmus  I in- 
cluded it  as  a synonym  of  S.  longus  (Trans.  Wis.  Acad.  Sci.,  Arts,  & 
Lett.  18^:  469.  1916)  but  am  now  convinced  that  it  should  be  con- 
sidered a distinct  variety.  The  cells  are  much  larger  than  the  typical 
form  but  unfortunately  Nageli  gives  neither  measurements  for  the  cells 
nor  an  indication  of  the  scale  of  magnification  of  his  drawings.  The 
measurements  stated  above  are  those  of  cells  from  Wisconsin  lakes. 
The  peculiar  arrangement  of  the  spines  that  Nageli  figures,  where  three 
adjacent  interior  cells  have  spines  on  the  same  end  and  none  on  the 
other  with  the  reverse  condition  in  the  remaining  interior  cells,  was 
found  to  be  a common  but  not  a constant  character  since  specimens  were 
found  with  spines  at  both  poles  of  interior  cells. 


WISCONSIN  PHYTOPLANKTON 


157 


ScENEDESMUs  ABUNDANS  (Kirchner)  Chodat.  PI.  39,  Figs.  23-25. 

Mater,  p.  la  fi.  crypt.  Suisse.  4*:  77.  3913;  G.  M.  Smith,  Trans.  Wis.  Acad.  Sci., 
Arts,  & Lett.  18^:  465,  pi,  31,  /ips.  137-140,  1916. 

Scenedesmus  quadricauda  var.  ahundans  (Kirchner)  Lagerheim,  5fvers. 
Kgl.  Vet.-Ak.  Forh.  39,  No.  2:  64,  pi.  2,  fig.  20.  1882. 

Coenobe  flat,  generally  4-celled.  Cells  ovoid  to  oblong-ellipsoid. 
Terminal  cells  with  1-2  spines  at  poles  and  additional  spines  on  outer 
face  between  the  poles.  Interior  cells  with  1-2  spines  at  each  pole. 
(Facultative  Planktont). 

Cells  4r-7  /A  broad,  7-12  ix  long.  4-celled  coenobia  7-12  fx  broad, 
15-30  fx  long.  Spines  4r-7.5  {x  long. 

Beaver  (2)  (rr),  Cochrane  (rr).  Diamond  (rr).  Grassy  (rr),  Horse  (rr), 
Long  (1)  (rrr),  Nancy  (rrr).  Palmer  (rr).  Poor  Farm  (ss). 

var.  LONGiCAUDA  G.  M.  Smith.  PI.  39,  Figs.  23-27. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18^:  467,  pi.  30,  -figs.  121-125.  1916. 

Cells  smaller,  ovoid.  Spines  much  longer  in  proportion  to  the  size 
of  the  cells.  (Facultative  Planktont). 

Cells  3-6  fx  broad,  7-9  fx  long.  4-celled  coenobia  7-9  fx  broad,  10-15 
fx  long.  Spines  6-10  (x  long. 

Camp  (rr),  Chain  (rrr).  Horse  (rr).  White  Ash  (rr). 

var.  BREViCAUDA  G.  M.  Smith.  PI.  40,  Figs.  3-5. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18':  468,  pi.  30,  figs.  126-132.  1916. 

Cells  ovoid,  smaller.  Spines  much  shorter  and  never  more  than 
three  between  the  polar  spines  of  terminal  cells.  (Facultative  Plank- 
tont). 

Cells  2.5-5  fx  broad,  5-8  fx  long.  4-celled  coenobia  5-8  fx  broad, 
10-13  fx  long.  Spines  1.5-3 .5  fx  long. 

Mendota  (rr). 

var.  ASYMMETRiCA  (Schroder)  G.  M.  Smith.  PL  40,  Figs.  6-8. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18':  468,  pi.  27,  figs.  45-46.  1916. 

Scenedesmus  quadricauda  var.  asymmetrica  Schroder,  Forschungsbr.  a.  d. 
Biol.  Stat.  zu  Plon  5:  45,  pi.  2,  figs.  5a-5c.  1897. 

Coenobia  generally  4-celled,  with  oblong-ellipsoid  cells.  Poles  of 
terminal  cells  with  a single  spine.  All  cells  of  coenobe  with  a single 
median  spine  perpendicular  to  the  plane  of  the  coenobe  and  at  one 
side  of  cell  only.  (Facultative  Planktont). 

Cells  2.5-4.5  y.  broad,  12-15  y long.  4-celled  coenobia  12-15  y broad, 
13-18  y long.  Spines  7-10  y long. 

Blue  Gill  (rr).  Wild  Goose  (rrr). 


158 


WISCONSIN  PHYTOPLANKTON 


ScENEDESMUS  QUADRicAUDA  (Turpin)  de  Brebisson.  PI.  40,  Figs.  9-11. 

Mem.  de  la  Soc.  Ac.  de  Falaise  1835:  66.  1835;  G.  S.  West,  Brit.  Preshw.  Algae 
220,  -figs.  92D-92F.  1904. 

Coenobia  flat,  of  2-4-8-16  (generally  4)  cells  in  a simple  linear  or 
snbalternating  series.  Cells  cylindrical-ovoid,  with  rounded  poles.  Poles 
of  terminal  cells  with  a single  long  straight  or  curved  spine.  Poles  of 
interior  cells  without  spines.  (Facultative  Planktont). 

Cells  3.5-6  [X  broad,  11-16  /a  long.  4-celled  coenobia  11-16  /a  broad, 
12-23  /A  long.  Spines  10-12  /a  long. 

Beaverdam  (rr).  Big  Butternut  (rrr),  Blake  (rr).  Browns  (rr).  Camp  (rr), 
Cketek  (rr).  Clam  (rr).  Clear  (rr).  Eagle  (rr).  East  (rrr),  Fislitrap  (rr). 
Green  (1)  (rr),  Hillman  (rr).  Horseshoe  (2)  (rr).  Lac  du  Flambeau  (rr), 
Lindy  (rr).  Little  Rice  (2)  (r).  Lost  (rr),  Loveless  (rr),  Lower  Nashotah 
(rr).  Lower  Nemahbin  (rr),  Mary  (rr),  Meta  (rr).  Mud  (1)  (rr).  Mud  (2) 
(rr),  Muskallonge  (r),  Nancy  (rr),  Okauchee  (rrr).  Old  Taylors  (rr)  Poke- 
gama  (1)  (rr),Pope  (rr).  Poplar  (rr).  Poor  Farm  (sss),  Rice  (1)  (rr).  Round 
(3)  (rr),  Sand  (1)  (rrr).  Sand  (4)  (rr),  Travis  (ccc).  White  Ash  (rr),  Wild 
Goose  (rrr),  Winnebago  (rr). 

The  most  ubiquitous  species  of  the  genus.  The  presence  of  spines 
on  the  poles  of  the  terminal  cells  only  is  the  distinguishing  feature  of 
the  species.  Cultural  work  has  shown  that  it  is  possible  to  recognize 
several  distinct  varieties  of  this  species. 


var.  PARVUS  G.  M.  Smith.  PI.  40,  Fig.  17. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  480,  pZ.  31,  Ms.  162-166.  1916. 

Cells  ovoid-cylindrical.  Length  of  cells  2-2.5  times  the  breadth  and 
equal  to  the  length  of  the  spines.  (Tychoplanktont). 

Cells  3-4  IX  broad,  5.5-8  /a  long.  4-celled  coenobia  5.5-8  /a  broad, 
12-15  IX  long.  Spines  4.5-8  /a  long. 

Deer  (rrr). 


var.  QUADRisPiNA  (Chodat)  G.  M.  Smith.  PI.  40,  Figs.  15-16. 
Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  479,  pi.  31,  figs.  167-171.  1916. 

Cells  broadly  ovoid,  about  twice  as  long  as  broad.  Spines  short, 
about  as  long  as  the  diameter  of  the  cell.  (Tychoplanktont). 

Cells  3.5-8  fx  broad,  8.5-15  /a  long.  4-celled  coenobia  8.5-15  ^ broad, 
16-32  fx  long.  Spines  2.5-5.5  /a  long. 

Mill  (rrr).  Pine  (rr),  Pokegama  (1)  (rrr),  Round  (1)  (rr).  Tied  Canoe 
(rrr). 


WISCONSIN  PHYTOPLANKTON 


159 


var.  LONGiSPiNA  (Chodat)  G.  M.  Smith.  PI.  40,  Figs.  12-14. 
Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  480,  pi.  31,  figs.  159-161.  1916. 

Cells  ovoid-cylindrical.  Length  of  cells  2.5  times  the  breadth.  (Fac- 
ultative Planktont). 

Cells  3.5-5  p,  broad,  8-11  jx  long.  4-celled  coenobia  8-11  /x  broad, 
12-20  fx  long.  Spines  7.5-10  fx  long. 

Horse  (rr).  Lost  (rr),  Mendota  (sss).  Palmer  (r). 

var.  Westii  G.  M.  Smith.  PI.  41,  Pigs.  3-7. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  18":  480,  pi.  32,  figs.  177-180.  1916. 

Cells  4.5-8  fx  broad,  16-22  p.  long.  4-celled  coenobia  16-22  p broad, 
25-35  p long.  Spines  12-16  p long.  (Facultative  Planktont). 

Bear  Trap  (rrr),  Blake  (rr).  Camp  (rr),  Cochrane  (rr),  Crawling  Stone 
(rr),  Grassy  (rr).  Horse  (rrr),  Lac  Court  Oreilles  (rr).  Loon  (rrr),  Meta 
(rr),  Silver  (2)  (rr). 

var.  MAXIMUS  W.  & G.  S.  West.  PI.  41,  Figs.  1-2. 

Trans.  Linn.  Soc.  2 Ser.  Bot.  5:  83,  pi.  5,  figs.  9-10.  1895. 

Cells  much  larger  and  spines  proportionally  longer.  (Facultative 
Planktont). 

Cells  9-11.5  p broad,  27-36  p long.  4-celled  coenobia  27-36  p broad, 
35^0  p long.  Spines  20-30  p long. 

Eagle  (rr),  Nicaboyne  (rr).  Pine  Tree  (rr).  Poor  Farm  (rr).  Tenderfoot' 
(rrr),  Travis  (r). 

SCENEDESMUS  OPOLiENSis  P.  Kichter.  PI.  41,  Figs.  8-11. 

Zeits.  f.  angw.  Mikr.  1:  7,  figs.  A-E.  1896. 

Coenobia  flat,  of  2-4-8  (generally  4)  cells  in  a single  linear  series. 
Interior  cells  naviculoid,  outer  margin  of  terminal  cells  straight  or 
slightly  convex.  Cells  in  lateral  contact  in  median  third  only.  Termi- 
nal cells  with  a long  spine  at  each  pole ; interior  cells  with  or  without 
long  or  short  spines.  Polar  spines  greatly  reduced  at  times.  (Faculta- 
tive Planktont). 

Cells  5-8  p broad,  12-28  p long.  4-celled  coenobia  12-28  p broad, 
15-30  p long.  Spines  5-28  p long. 

Palmer  (rr). 

The  navicular  shape  of  the  cells,  their  lateral  contact  in  the  median 
third  only,  together  with  the  beak-like  instead  of  rounded  apex  sepa- 
rates this  species  from  S.  quadricauda. 


160 


WISCONSIN  PHYTOPLANKTON 


Sub-family  C0ELA8TREAE. 

Coenobia  forming  a sphere  with  the  cells  radially  arranged  in  a single 
layer  around  a common  center.  The  number  of  cells  in  a coenoba  al- 
ways a multiple  of  two.  Cells  spherical,  polygonal,  or  elongate  cylindri- 
cal. 


KEY  TO  THE  GENERA. 

Cells  spherical,  polygonal,  or  flattened;  length  never  more  than  twice  the 


breadth. 

Cells  without  spines  on  the  outer  face Coelastrum 

Cells  with  spines  on  outer  face Sorastrum 

Cells  3-7  times  as  long  as  broad Actinastrum 


COELASTRUM  Nageli  1849. 

Coenobe  a hollow  sphere  of  2-4-8-16-32-64-128  cells.  Cells  spheri- 
cal, ovoid,  or  pyramidal ; compressed  or  with  large  intercellular  spaces ; 
enclosed  in  a very  delicate  gelatinous  sheath.  Daughter  coenobia  some- 
times remaining  joined  in  multiple  coenobia  by  the  remains  of  the  old 
mother  cell  wall. 

Reproduction  by  autocolony  formation  in  any  cell  of  the  coenobe. 
Liberation  of  young  coenobia  by  a rupture  of  old  mother  cell  wall. 

KEY  TO  THE  SPECIES. 

Cells  spherical. 

Processes  uniting  the  cells  long C.  Reticulatxjm 

Processes  uniting  the  cells  short. 

External  face  of  cells  without  projections C.  Microporum 

External  face  of  cells  with  short  truncate  projections. . .C.  Cambricum 
Cells  truncate  cones ....C.  Proboscideum 

Coelastrum  microporum  Nageli.  PI.  41,  Figs.  12-13;  PI.  42,  Fig.  1. 
in  Braun,  Alg.  unicell.  70.  1855;  Senn,  Bot.  Ztg.  57:  53,  pi.  2,  iigs.  11-17.  1899. 

Coenobia  spherical  to  ovoid ; with  8-16-32-64  cells.  Cells  spherical, 
enclosed  by  a delicate  gelatinous  sheath  and  connected  to  one  another 
by  short,  stout,  gelatinous  processes.  Intercellular  interstices  smaller 
than  the  diameter  of  the  cells.  (Facultative  Planktont). 

Diam.  cells  (without  sheath)  3-20  p,;  (with  sheath)  4-23  p,.  Diam. 
coenobia  20-90  p. 

Balsam  (rrr).  Bear  (1)  (rr),  Bear  (2)  (rr).  Bear  Trap  (rrr),  Big  Butter- 
nut (rrr),  Blake  (rrr).  Bone  (rrr),  Boulder  (rrr).  Browns  (rr).  Center 
(rr),  Chetac  (rr),  Cochrane  (rr).  Deer  (rrr).  East  (rrr),  Elizabeth  (rr), 
Fishtrap  (rrr),  Granite  (rr).  Hill  (rr),  Hillman  (rrr).  Horseshoe  (2)  (rrr), 


WISCONSIN  PHYTOPLANKTON 


161 


Island  (rr),  Lac  du  Flambeau  (sss),  Little  Bass  (2)  (rr),  Little  Butternut 
(rr),  Little  Crooked  (rrr),  Little  Doctor  (rr).  Loveless  (rrr),  Lower  Naah- 
otah  (rrr).  Lower  Turtle  (rr),  Mary  (rr),  Mendota  (sss),  Mill  (rrr),  Mud  (2) 
(rr),  Nancy  (rrr),  Oconomowoo  (rr).  Otter  (rrr),  Pewaukee  (rrr).  Pine  Tree 
(rrr),  Pokegama  (1)  (rr),  Pokegama  (2)  (rr).  Poor  Farm  (rrr).  Pope  (rrr), 
Prairie  (rrr).  Round  (1)  (rrr).  Sand  (1)  (rr).  Sand  (4)  (rr).  Shell  (rrr). 
Silver  (1)  (rr).  South  Turtle  (rr).  Squirrel  (rr).  Tenderfoot  (rr).  Tied  Canoe 
(rrr),  Travis  (rrr).  Vermilion  (rr),  White  Ash  (rrr),  White  Sand  (rrr). 
Wolf  (rrr). 

A species  that  is  found  in  all  types  of  lakes. 

CoELASTRUM  CAMBRicuM  Archer.  PL  42,  Figs.  2-3. 

Quart.  Jour.  Micr.  Sci.  N.  S.  8:  65.  1868;  W.  West,  Jour,  of  Bot.  31:  99,  pZ. 
333,  lig.  14.  1893. 

Coenobia  spherical,  of  8-16-32-64r-128  (generally  32)  cells.  Cells 
spherical,  with  a single  truncate  projection  on  the  outer  face.  Each 
cell  connected  to  adjacent  ones  by  short,  somewhat  flattened,  gelatinous 
projections.  Small  circular  or  triangular  interstices  between  the  cells. 
( Facultative  Planktont ) . 

Diam.  cells  (with  sheath)  6-21  /a,  (without  sheath)  5-18  /a.  Diam. 
coenobia  20-100  /a. 

Balsam  (rrr).  Bear  (2)  (rr),  Beaverdam  (rr),  Birch  Island  (rrr).  Blue 
Gill  (rrr).  Catfish  (rr),  Cochrane  (rrr).  Cranberry  (rr).  East  (rr).  Found 
(rr),  Hillman  (rrr),  Jag  (rr).  Little  Bass  (2)  (r),  Mercer  (rr).  Middle  Mc- 
Kenzie (rrr),  Minocqua  (rr),  Nancy  (rrr),  Nicaboyne  (rr).  Old  Taylors  (rrr), 
Owen  (rrr).  Pine  (1)  (rr).  Pine  Tree  (rr),  Pokegama  (1)  (rr).  Prairie  (rr), 
Rudolph  (rrr),  St.  Croix  (rr).  Silver  (1)  (rr),  Streitor  (rr),  Travis  (r). 
Wild  Goose  (rrr). 

CoELASTRUM  RECTicuLATUM  (Dangcard)  Senn.  PI.  42,  Figs.  4-6. 
Bot.  Ztg.  57:  66,  pi.  2,  figs.  1-10.  1899. 

Coenobia  spherical,  of  8-16-32  cells ; generally  held  in  multiple  coe- 
nobia by  the  remains  of  old  mother  cell  walls.  Cells  spherical,  enclosed 
by  a narrow  gelatinous  sheath  and  connected  to  adjacent  cells  by  6-9 
long,  slender,  tough,  gelatinous  processes.  (Facultative  Planktont). 

Diam.  cells  (with  sheath)  6-24  fi.  Diam.  coenobia  10-65  /a. 

Bear  Trap  (rrr).  Bear  (3)  (rr),  Beaverdam  (rrr).  Big  McKenzie  (rrr), 
Birch  (2)  (rr),  Blake  (rrr).  Browns  (ss).  Camp  (rr).  Fish  (rr).  High  (rrr). 
Island  (rr).  Lac  Court  Oreilles  (rr).  Little  Bass  (2)  (rr),  Mary  (rr),  Mendota 
(rr).  Mud  (1)  (rr),  Mudhen  (rr),  Nancy  (rr).  North  Twin  (rrr).  Palmer  (rr). 

The  long  processes  connecting  the  cells  distinguish  this  species  from 
all  others.  Solitary  coenobia  are  rarely  met  with  since  the  long  proc- 
esses hinder  the  escape  of  young  coenobia. 


11 


162 


WISCONSIN  PHYTOPLANKTON 


CoELASTRUM  PROBOSCiDEUM  Bohlin.  PI.  42,  Figs.  7-8 ; PI.  43,  Figs.  1-2. 
Bih.  t.  Kgl.  Sv.  Vet.-Ak.  Handl.  23,  Afd.  3,  No.  7:  33,  pi.  2,  figs.  19-22.  1897. 

Coenobia  pyramidal  or  cubical,  rarely  polygonal;  of  4^8-16-32  (gen- 
erally 4 or  8)  cells;  frequently  joined  in  compound  coenobia  of  irregu- 
lar shape.  Cells  truncate  cones,  at  times  with  concave  sides ; with  base 
of  cone  towards  the  center  of  coenobe.  Interstices  between  cells  large, 
polygonal.  Chloroplast  single,  parietal,  with  one  pyrenoid.  (Faculta- 
tive Planktont). 

Diam.  cells  6.5-17  /x;  diam.  4-celled  coenobia  12-35  /x;  compound 
coenobia  up  to  350  /x  in  diam. 

Bear  Trap  (rrr),  Cochrane  (rr),  Durchmans  (rrr),  Pine  Tree  (aa).  Round 
(rrr). 

The  appearance  of  this  alga  as  the  dominant  organism  of  the  plankton 
of  Pine  Tree  lake  is  of  particular  interest  since  Coelastrum  species  have 
not  been  reported  as  occurring  in  abundance  by  any  student  of  the 
phytoplankton.  Compound  coenobia  were  very  common  and  it  was  not 
at  all  unusual  to  find  50-80  four-  or  eight-celled  coenobia  joined  in  one 
irregular  mass.  The  cells  of  four-celled  coenobia  are  tetrahedrically 
arranged  in  the  manner  that  G.  S.  West  has  described  them  for  Coelas- 
irum  compositum  (Jour.  Linn.  Soc.  Bot.  38:  136,  pi.  5,  figs.  8-9.  1907) 
and  I believe  that  G.  compositum  should  be  considered  a synonym  of 
C.  prohoscideum.  The  cellular  arrangment  of  eight-celled  coenobia  is 
exactly  as  Bohlin  and  Senn  describe.  In  the  sixteen-celled  coenobia, 
which  are  of  very  rare  occurrence,  the  cells  form  a hollow  sphere  so  that 
the  general  appearance  of  the  colony  resembles  the  other  species  of  the 
genus.  This  difference  in  ceU  number  is  of  minor  significance,  the 
number  of  cells  in  a colony  being  dependent  upon  the  vegetative  vigor 
of  the  mother  cell  at  the  time  colony  formation  takes  place. 

SORASTRUM  Kutzing.  1845. 

Cells  pyriform,  semilunar,  or  reniform;  united  to  form  spherical 
colonies  of  8-16-32-64-128  cells.  Center  of  colony  a polyhedral  body 
from  which  gelatinous  strands  radiate  to  each  cell.  Distal  side  of  cells 
with  1,  2,  or  4 spines.  Chloroplast  diffuse,  with  one  pyrenoid. 

Reproduction  unknown ; presumably  by  autocolonies  as  in  Coelastrum^ 
possibly  by  zoospores  as  in  Pediastrum. 


WISCONSIN  PHYTOPLANKTON  163 

KEY  TO  THE  SPECIES. 

Spines  on  outer  face  of  cells  short  (4-8  /*) S.  SpiNuiiOSUM 

Spines  on  outer  face  of  cells  long  (10-15  /*) S.  Amebicanum: 


SoRASTRUM  SPINULOSUM  Nageli.  PL  44,  Figs.  4-5. 

Gatt.  einz.  Algen  99,  pi.  5,  -figs.  Da-Dd.  1849;  G.  S.  West,  Brit.  Preshw.  Algae 
215,  figs.  89A-89B.  1904. 

Coenobe  of  4-8-16-32  cells.  Cells  broadly  renifonn  to  cuneate,  with 
four  short  horns  at  the  corners  of  the  outer  face.  Stipe  leading  to 
sphere  at  center  of  colony  short.  Chloroplast  single,  generally  filling 
the  entire  cell;  pyrenoid  single.  (Tychoplanktont). 

Cells  8-20  {X  broad,  6-18  ix  long,  5-8  fx  thick.  Horns  of  adult  cells 
4-8  fx  long. 

Hillman  (rrr),  Horse  (rrr). 

SoRASTRUM  AMERiCANUM  (Bohlin)  Schmidle.  PI.  44,  Fig.  1. 

Engl.  Jahrb.  27:  230.  1900:  Lemmermann,  Arch.  f.  Hydrob.  u.  Planktonkde. 
5:  310,  fig.  5.  1910. 

Selenosphaerium  americanum  Bohlin,  Bib.  t.  Kgl.  Sv.  Vet.-Ak.  Handl.  23, 
Afd.  3,  No.  7:  40,  pi.  2,  figs.  38-41.  1897. 

Coenobia  spherical,  solitary,  of  16-32-64-128  (generally  16  or  32) 
cells.  Cells  cardiate  to  pyramidate,  somewhat  flattened,  with  the  apex 
towards  the  center  of  the  coenobe  and  ending  in  a broad  gelatinous 
stalk  as  long  as  the  cell.  Stalk  cylindrical,  5-6  faceted  at  the  base; 
with  the  facets  in  contact  with  those  of  other  stalks  and  forming  a hol- 
low sphere.  Outer  face  of  cells  emarginate,  with  a single  long  spine  at 
each  of  the  four  corners.  (Facultative  Planktont). 

Cells  7-20  fx  broad,  5-20  fx  long  (without  stalk),  4^S  fx  thick.  Spines 
of  adult  cells  10-15  fx  long. 

Devils  (1)  (rr),  Devils  (2)  (rrr),  Nancy  (rrr),  Travis  (rr). 

The  longer  spines  and  stalk,  together  with  the  more  prominent  central 
sphere,  separates  this  species  from  the  foregoing. 

var.  UNDULATUM  G.  M.  Smith.  PI.  44,  Figs.  2-3. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  640,  pi.  13,  fig-  7.  1918. 

Sides  of  facets  at  base  of  stipe  undulate.  Dimensions  as  in  the  typi- 
cal form.  (Facultative  Planktont). 


Beaverdam  (rrr). 


164 


WISCONSIN  PHYTOPLANKTON 


ACTINASTRUM  Lagerheim  1882. 

Coenobia  free-floating,  of  4-8-16  (generally  8),  ovoid,  cylindrical, 
club-shaped,  or  drum  stick  shaped  cells  radiating  from  a common  cen- 
ter. Coenobia  sometimes  united  to  form  multii^’e  coenobia  of  irregular 
shape.  Each  cell  with  a single,  laminate,  parietal  chloroplast;  with 
or  without  pyrenoids. 

Reproduction  by  longitudinal  and  transverse  division  of  the  contents 
of  any  cell,  the  young  autocolony  being  liberated  by  a rupture  of  the 
mother  cell  wall. 


KEY  TO  THE  SPECIES. 


Center  of  cell  twice  as  broad  as  poles A.  Hantzsc?hi 

Center  of  cells  about  the  same  width  as  the  poles A.  Graciulimum 


Actinastrum  GRAciLLiMUM  G.  M.  Smith.  PI.  43,  Figs.  3-5. 

Bull.  Torr.  Bot.  Cl.  43:  480,  pi.  26,  fig.  23.  1916. 

Coenobia  of  4 or  8 cells  radiating  from  a common  center.  Cells  elon- 
gate-cylindrical, tapering  but  slightly  to  a truncate  end,  7-10  times  as 
long  as  broad.  Chloroplast  single,  parietal,  laminate,  with  or  without 
a pyrenoid.  (Euplanktont). 

Cells  1.75-3  fx  broad,  14-21  long;  colonies  30-45  fi  in  diam. 

Horse  (rr),  Kegonsa  (rrr),  Mendota  (rr). 

The  species  differs  from  the  following  in  the  very  slight  dilation  of 
the  median  portion  of  the  cell  and  the  greater  proportional  length. 

Actinastrum  Hantzschi  Lagerheim.  PI.  43,  Figs.  6-7. 

Ofvers.  Kgl.  Vet.-Ak.  Porh.  39,  No.  2:  70,  pi.  3,  figs.  25-26.  1882. 

Coenobia  of  4 or  8 cells  radiating  from  a common  center.  Coenobia 
sometimes  united  to  form  multiple  coenobia.  Cells  3-6  times  as  long 
as  broad,  with  truncate  poles,  ovoid-cylindrical.  Diameter  of  middle 
of  cells  twice  that  of  poles.  Chloroplast  single,  parietal,  laminate ; with 
one  pyrenoid.  (Euplanktont). 

Cells  3-6  fi  broad,  10-26  fx  long ; coenobia  up  to  50  fx  in  diam ; com- 
pound coenobia  up  to  200  fx  in  diam. 

Chetek  (rr),  Kegonsa  (r).  Lower  Turtle  (rrr),  Mendota  (rr),  Prairie  (rr). 
Upper  Turtle  (rr),  Waubesa  (rrr). 

Multiple  coenobia  are  of  rare  occurrence  and  have  only  been  found 
in  the  plankton  of  Chetek  lake.  This  may  be  due  to  the  fact  that  such 
colonies  readily  fragment  into  the  individual  coenobia  and  the  handling 
incident  to  the  collection  of  samples  is  sufficient  to  break  up  multiple 
coenobia. 


WISCONSIN  PHYTOPLANKTON 


165 


var.  ELONGATUM  G.  M.  Smith.  PI.  43,  Fig.  8. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Liett.  19^:  636,  pi.  12,  -fig.  3.  1918. 

Colonies  of  4 or  8 cells.  Cells  cylindrical,  tapering  but  little  towards 
the  poles.  ( Euplanktont) . 

Cells  4^5  II  broad,  30-35  long. 

Bear  (3)  (rr). 

The  cells  of  this  variety  are  much  longer  than  those  of  the  typical 
form. 


Family  HYDRODICTYACEAE. 

Cells  cylindrical,  or  flattened  and  hexagonal  to  trapezoidal  with  one, 
two,  or  four  projections.  Coenobia  of  definite  shape;  cylindrical  with 
a large  number  of  cells;  or  disciform  with  2-4-8-16-32-64-128  cells. 
Cells  incapable  of  division  after  their  formation.  Chloroplast  single, 
parietal,  laminate  to  reticulate,  frequently  filling  the  entire  mature 
cell ; with  one  to  many  pyrenoids. 

Asexual  reproduction  by  the  divisioli  of  contents  of  any  cell  to  form 
zoospores  that  swarm  within  old  cell  wall  or  within  a gelatinous  vesicle 
extruded  from  the  cell.  Zoospores  becoming  apposed  in  the  shape  of 
the  adult  cell  when  they  come  to  rest. 

Sexual  reproduction  by  isogamous  zoogametes  which  fuse  in  pairs  to 
form  angular  resting  cells  which  form  colonies  on  their  germination. 


KEY  TO  THE  GENERA. 


Coenobe  a hollow  cylindrical  tube  with  rounded  ends Hydeodictyon 

Coenobe  a flattened  disc  one  cell  in  thickness. 

Number  of  cells  in  coenobe  always  2 Etjasteopsis 

Number  of  cells  in  coenobe  4-8-16-32-64-128,  very 

rarely  2 Pediastbum 


HYDRODICTYON  Roth  1800. 

Cells  macroscopic,  oblong-cylindrical  with  rounded  ends;  united  to 
form  a free-floating,  reticulate,  saccate  coenobium.  Meshes  of  nets 
3-12  (generally  5-6)  sided.  Cells  coenoeytic;  chloroplast  parietal, 
reticulate  at  first,  later  diffuse;  pyrenoids  single  in  very  young  cells, 
several  hundred  in  mature  cells. 

Asexual  reproduction  by  the  division  of  cell  contents  into  very  many 
biciliate  zoospores  which  swarm  about  in  and  become  arranged  as  in 
the  mature  coenobe  within  the  old  mother  cell  wall.  Liberation  of  the 
young  coenobe  by  a gradual  gelatinization  of  the  mother  cell  wall. 

Sexual  reproduction  by  zoogametes  which  are  similar  in  structure  to 


166 


WISCONSIN  PHYTOPLANKTON 


zoospores  but  smaller,  the  zoogametes  fusing  in  pairs  to  form  a spheri- 
cal zygote  after  their  liberation  through  a pore  in  the  cell  wall.  Zygote 
germinating,  after  a short  period  of  rest,  into  2-5  large  uni-  or  biciliate 
zoospores  that  form  irregular  polyhedral  cells  on  coming  to  rest.  Poly- 
eders  ultimately  germinating  into  200-300  zoospores  that  are  liberated 
in  a vesicle  and  form  a net  as  in  asexual  reproduction. 

Hydrodictyon  reticulatum  (L)  Lagerheim.  PI.  44,  Fig.  6;  PI.  45, 

Fig.  1. 

dfvers.  Kgl.  Vet.-Ak.  Forh.  40,  No.  2:  71.  1883;  G.  S.  West,  Brit.  Freshw.  Algae 
208,  figs.  84A-84F.  1904 

Cells  elongate  cylindrical,  forming  a definite  closed  net.  (Tycho- 
pJanktont) . 

Cells  5-250  ii  broad,  up  to  1.5  cm.  long.  Coenobia  up  to  30  cm.  long. 
Little  Bass  (2)  (rr),  Mendota  (rr),  Monona  (sss). 

An  alga  that  is  in  no  sense  a plankton  organism  but  one  which  some- 
times grows  in  abundance  in  shallow,  well  protected  bays  and  so  may, 
at  times,  be  found  free-floating  in  large  patches  a considerable  distance 
from  the  shore. 


PEDIASTKUM  Meyen  1829. 

Coenobia  disciform  to  stellate,  free-floating,  of  2-4-8-16-32-64-128 
cells  arranged  in  a layer  one  cell  in  thickness.  Coenobe  entire,  perfor- 
ate, or  clathrate.  Marginal  cells  polygonal,  with  one,  two,  or  four  proc- 
esses that  sometimes  terminate  in  a tuft  of  long  hyaline  setae.  Interior 
cells  polygonal,  without  processes.  Cell  wall  smooth,  granulate,  or 
covered  with  a meshwork  of  fine  ridges;  without  a gelatinous  sheath. 
Chloroplasts  parietal  and  disciform  at  first,  later  filling  the  entire  cell ; 
with  1-4  pyrenoids.  Cells  coenoc5d;ic. 

Asexual  reproduction  by  the  division  of  contents  of  any  cell  into 
2-4-8-16-32-64-128  biciliate  zoospores  that  are  extruded  in  a gelatinous 
vesicle  and,  after  a short  period  of  swarming,  on  becoming  quiescent 
appose  themselves  in  the  same  position  as  the  mature  cells  of  the 
coenobe. 

A fusion  of  biciliate  zoogametes  into  polyhedral  resting  cells  has  been 
observed.  On  germination  these  zygospores  form  8-16-32  zoospores 
that  behave  as  in  asexual  reproduction. 


WISCONSIN  PHYTOPLANKTON 


167 


KEY  TO  THE  SPECIES. 

Outer  face  of  marginal  cells  without  projections. 

W all  smooth p.  Integrum 

Wall  reticulate P.  Araneosum 

Outer  face  of  marginal  cells  with  1,  2,  or  4 projections. 

Marginal  cells  with  more  than  one  projection. 

Cells  on  margin  with  four  projections  and  a deep  linear  incision.  .P.  Tetras 


Cells  on  margin  with  two  projections. 

Coenobe  entire. 

Cell  wall  smooth  or  punctate. 

Projections  side  by  side  in  front  view  of  cell P.  Boryanum 

Projections  above  one  another  in  front  view P.  Kawraiskyi 

Cell  wall  reticulate. 

Wall  covered  with  coarse  reticulations P.  Araneosum 

Wall  covered  with  fine  reticulations P.  Sculptatum 

Coenobe  perforate. 

Ends  of  projections  truncate P.  Duplex 

Ends  of  projections  incised P.  Biradiatum 

Marginal  cells  with  one  projection P.  Simplex 


Pediastrum  simplex  var.  duodenarium  (Bailey)  Rabenhorst.  PL  45, 

Figs.  2-6. 

Fl.  Eur.  Algarum  3:  72.  1868. 

Monactinns  duodenarius  Bailey,  Smithsonian  cont.  to  knowl.  7,  Art.  3:  14, 
pi.  1,  fig.  37.  1855. 

Monactinus  octonarius  Bailey,  iMd.  p.  14,  pi.  1,  fig.  36.  1855. 

Pediastrum  simplex  var.  clatfiratum  (Schroter)  G.  S.  West,  Jour.  Linn.  Soc. 
Bot.  38:  134.  1907. 

Coenobia  circular  to  oval,  of  4-8-16-32-64-128  (generally  8-16-32) 
cells.  Inner  face  of  marginal  cells  concave,  outer  face  produced  into 
a single,  delicately  tapering,  concave  process  frequently  furnished  with 
a tuft  of  delicate  hyaline  setae.  Interior  cells  as  those  of  the  periphery 
but  with  shorter  processes.  Interstices  between  cells  large.  Cell  wall 
smooth  or  finely  punctate.  (Facultative  Planktont). 

Cells  10-24  fl  broad,  20-45  fi  long. 

Balsam  (rr).  Bear  (1)  (r).  Bear  Trap  (rrr),  Blake  (r),  Camp  (rr).  Green 
(1)  (rrr).  High  (rr),  Hillman  (rrr),  Kegonsa  (rr).  Little  Bass  (rr),  Little 
Butternut  (r).  Little  Crooked  (rrr),  Lost  (rr).  Loveless  (rrr),  Mary  (rr), 
Monona  (r).  Mud  (2)  (rr).  Palmer  (rrr),  Pokegama  (1)  (sss).  Rice  (1)  (r), 
St.  Croix  (rr),  Silver  (1)  (rr).  Spirit  (rr).  Upper  Turtle  (r).  Vermilion  (cc), 
Wapagossett  (r).  White  Ash  (rr),  Winnebago  (rr).  Wolf  (rrr). 

This  alga  is  one  that  has  been  given  a number  of  names  by  various  in- 
vestigators, but  for  the  reasons  stated  elsewhere  (Trans.  Wis.  Acad.  Sci., 
Arts,  & Lett.  19^:  642.  1918)  I consider  the  one  given  above  the  proper  . 


name. 


168 


WISCONSIN  PHYTOPLANKTON 


Pediastrum  integrum  Nageli,  PI.  45,  Fig.  7. 

Gatt.  einz.  Algen  97,  p?.  5,  figs.  B4a^B4r.  1849. 

Coenobia  8-16-32-64-celled,  circular  or  oval,  without  perforations. 
Interior  cells  polygonal;  marginal  cells  5-6  sided,  at  times  with  rudi- 
ments of  two  projections  that  are  sometimes  reduced  to  a single  wart, 
but  generally  without  projections.  Cell  wall  smooth  or  punctate. 

( Tychoplanktont) . 

Diam.  cells  15-30  /x. 

Soft  (rrr). 

var.  PRiVA  Printz.  PI.  45,  Pigs.  &-10. 

Skr.  Vidensk.  i Kristiana  Mat.-Naturv.  Kl.  1913':  No.  6:  73,  pi.  5,  fig.  147. 
1914. 

Coenobia  generally  8-celled.  Marginal  cells  trapezoidal,  without  in- 
cisions or  processes.  Interior  cells  polygonal,  without  incisions.  Cell 
wall  smooth.  (Facultative  Planktont). 

Diam.  cells  8-10  /x.  Diam.  8-celled  coenobia  15-25  /x. 

Palmer  (rr). 

The  general  shape  of  the  cells  is  like  that  of  P.  tetras  but  since  there 
are  no  incisions  in  the  cells  they  cannot  be  placed  among  the  varieties 
of  P.  tetras. 

Pediastrum  araneosum  Raciborski.  PI.  45,  Fig.  11. 

Mem.  Acad.  Imp.  Sci.  Cracow  20:  84.  1890. 

Coenobia  circular  to  oval,  without  perforations,  of  8-16-32-64-128 
cells.  Interior  cells  in  contact  with  4^6  other  cells,  straight  sided.  In- 
ner half  of  marginal  cells  similar  to  interior  cells,  outer  half  without 
processes  but  with  a deep  emargination.  Surface  of  cell  covered  with 
a coarse  reticulum  of  ridges.  (Facultative  Planktont). 

Diam.  cells  15-32  /x. 

Birch  Island  (rr),  Blue  Gill  (rrr),  Boulder  (rrr),  Carson  (rrr).  Deer  (rrr). 
Devils  (1)  (rrr),  Diamond  (rrr),  Dutchmans  (rr).  Horseshoe  (1)  (rr).  Lake 
of  the  Woods  (rrr),  Lindy  (rr).  Loon  (rrr),  Nicahoyne  (rr),  Nancy  (r).  Pine 
Tree  (rr),  Pokegama  (1)  (rrr).  Poor  Farm  (rrr).  Sand  (2)  (rr),  Wild 
Goose  (rr). 

var.  RUGULOSUM  (G.  S.  West)  G.  M.  Smith.  PI.  45,  Figs.  12-13. 
Bull.  Torr.  Bot.  Cl.  43:  476,  pi.  25,  fig.  14.  1916. 

Sides  of  cells  undulate  where  they  are  in  contact  with  one  another. 
(Facultative  Planktont). 

Meta  (r). 


WISCONSIN  PHYTOPLANKTON 


169 


Pediastrum  sculptatum  G.  M.  Smith.  PI.  46,  Fig.  1. 

Bull.  Torr.  Bot.  Cl.  43:  475,  pL  25,  fig.  13.  1916. 

Coenobia  oval  to  circular,  of  8-16-32  cells.  Interior  cells  with  4-6 
straight  sides,  with  a few  interstices  between  the  cells.  Marginal  cells 
bilobed,  with  the  lobes  produced  into  two  short  divergent  or  parallel 
processes.  Cell  wall  covered  with  a network  of  very  fine  ridges.  (Fac- 
ultative Planktont) . 

Diam.  cells  10-15  ju,.  Diam.  coenobia  80-150  /x. 

South  Turtle  (rr). 


Pediastrum  Boryanum  (Turpin)  Meneghini.  PI.  46,  Figs.  2-7. 

Linnaea  14:  210.  1840;  G.  S.  West,  Brit.  Freshw.  Algae  211,  figs.  85f-85h. 
1904. 

Coenobia  circular  to  ovoid,  of  4^8-16-32-64^-128-256  (generally  8- 
16-32)  cells  that  are  normally  compactly  arranged  in  concentric  rings. 
Interior  cells  4-6  sided,  with  straight  sides.  Inner  half  of  marginal 
cells  similar  to  interior  cells ; outer  half  produced  into  two  short  obtuse 
processes  ending  in  short  spines,  slightly  to  deeply  emarginate  between 
the  processes.  Projections  on  outer  face  and  their  spines  sometimes 
greatly  reduced.  Wall  smooth  or  granulate.  (Facultative  Planktont). 

Diam.  cells  7.5-30  /x.  Diam.  16-celled  coenobia  40-100  (i. 

Balsam  (rrr).  Bear  (1)  (rrr),  Bear  (2)  (rrr).  Bear  (3)  (ss).  Bear  Trap 
(rr),  Beasley  (rr),  Beaver  (rr),  Beaverdam  (ss).  Big  Butternut  (rr),  Birch 
Island  (rr),  Blake  (rr).  Bloom  (r),  Boulder  (rrr),  Browns  (rr).  Camp  (r), 
Carroll  (sss),  Carson  (rrr),  Catherine  (rr).  Center  (ss),  Chetac  (rr),  Chetek 
(rrr).  Clear  Crooked  (rr),  Cochrane  (rrr).  Crawling  Stone  (rr).  Deer  (r),  Des 
Moines  (rr).  Devils  (1)  (rr).  Eagle  (sss).  East  (rrr),  Elizabeth  (rrr).  Fence 
(rrr),  Fishtrap  (rr).  Found  (rr),  Fowler  (rrr),  Geneva  (rr),  Granite  (rr), 
Grassy  (rr).  Green  (2)  (rrr).  Grindstone  (rr).  Half  Moon  (rrr),  Harris  (rr). 
High  (rr),  Hillman  (rr).  Hooker  (rr).  Horse  (rrr).  Horseshoe  (1)  (ss), 
Kawaguesaga  (r),  Kegonsa  (sss).  Kitten  (rr).  Lac  la  Belle  (rr).  Lac  Court 
Oreilles  (rr).  Lac  du  Flambeau  (r),  Lindy  (rr).  Little  Bass  (2)  (r).  Little 
Bear  (sss).  Little  Butternut  (rrr).  Little  Crooked  (rr).  Little  Rice  (2)  (rr). 
Little  Wood  (rrr).  Long  (2)  (rr).  Long  (3)  (rrr).  Loveless  (r).  Lower  Nash- 
otah  (rrr).  Lower  Nemahbin  (rr).  Lower  Turtle  (rr).  Marl  (rr),  Mary  (ss), 
Mendota  (ss),  Monona  (ss).  Mud  (1)  (r).  Mud  (2)  (r),  Mudhen  (rr),  Muskal- 
loDge  (rr),  Nagawicka  (rr),  Nancy  (sss),  Nicaboyne  (rrr),  Oconomowoc  (rr). 
Old  Taylors  (rr),  Owen  (r).  Paddock  (rrr),  Pewaukee  (rr).  Pine  (2)  (rrr), 
Pokegama  (1)  (sss),  Pokegama  (2)  (r),  Pokegama  (3)  (rr).  Poor  Farm  (rr). 
Poplar  (rr).  Prairie  (rrr).  Rainbow  (rr).  Reserve  (rrr),  Rice  (1)  (rr).  Round 
(1)  (sss).  Round  (2)  (rr),  St.  Croix  (rr).  Sand  (1)  (rrr).  Sand  (3)  (rrr), 
Sand  (4)  (sss).  Silver  (2)  (r),  Spirit  (rr).  Star  (rr),  Streitor  (rr),  Taylor 
(r).  Tenderfoot  (rrr).  Tied  Canoe  (rrr).  Turtle  [North  and  South]  (rr),  Up- 


170 


WISCONSIN  PHYTOPLANKTON 


per  Turtle  (r),  Vermilion  (rr),  Waubesa  (r),  White  Ash  (sss),  Whitefish  (rr), 
White  Sand  (rr).  Wildcat  (rrr),  Winnebago  (r),  Wolf  (s). 

A species  that  is  almost  universally  present  and  one  which  varies 
greatly  in  the  character  of  the  marginal  cells. 

var.  UNDULATUM  Wille.  PI.  46,  Fig.  8. 

Ofvers.  Kgl.  Vet.-Ak.  Forh.  36,  No.  5:  28.  187'9. 

Sides  of  cells  in  contact  with  other  cells  undulate  instead  of  straight. 
( Tychoplanktont) . 

Winnebago  (rr). 

var.  LONGICORNE  Kaciborski.  PI.  46,  Fig.  9. 

Akad.  Umiej.  w.  Krakowie  20:  13.  1889;  Printz,  Skr.  Vidensk.  i Kristiana 
Mat.-Natury.  Kl.  1913,  No.  6:  74,  pi,  5,  fig^  149.  1914. 

Horns  at  the  ends  of  processes  much  longer  than  typical  form,  some- 
times swollen  at  apex.  Cell  wall  smooth  or  granulate. 

Diam.  cells  up  to  40  fx.  Horns  12-30  [x  long. 

Bone  (rrr). 

Raciborski  recognizes  the  forms  glabrum  and  granviatum  but,  judg- 
ing by  the  variation  in  the  nature  of  the  wall  in  the  typical  form,  these 
forms  should  not  be  recognized. 

Pediastrum  Kawraiskyi  Schmidle.  PI.  46,  Figs.  10-13. 

Arb.  d.  Botan.  Gartens  zu  Tiflis  2:  269.  1897;  Nitardy,  Beih.  z.  Bot.  Cent.  32-: 
164,  pi.  5,  fig.  6.  1914. 

Coenobia  of  16-32-64  cells  that  are  compactly  arranged.  Interior 
cells  4—6  sided,  sides  straight.  Inner  half  of  marginal  cells  as  interior 
cells,  outer  half  with  two  short  projections  that  lie  one  above  the  other 
when  the  coenobe  is  seen  in  surface  view.  Cell  wall  smooth.  (Eu- 
pJanktont). 

Diam.  cells  9-22  fx.  Diam.  32-celled  coenobia  60-100  /a. 

Big  Bass  (r).  Palmer  (rr).  Tenderfoot  (rrr),  Winnebago  (r). 

The  cell  shape  is  quite  similar  to  P.  Boryanum  but  the  peculiar  posi- 
tion of  the  processes  on  the  marginal  cells  at  once  distinguishes  this 
species  from  all  others.  Some  investigators  are  inclined  to  the  view 
that  P.  Kawraiskyi  is  but  a passing  condition  of  P.  Boryanum  that  is 
found  for  one  generation  only.  I have  grown  P.  Boryanum  in  pure 
cultures  for  several  years  and  have  never  seen  a single  coenobe  with  the 
projections  of  marginal  cells  lying  one  above  the  other,  and  so  feel  con- 
fident that  P.  Kawraiskyi  is  not  a temporary  growth  condition  of 
P.  Boryanum. 


WISCONSIN  PHYTOPLANKTON 


171 


Pediastrum  duplex  Meyen.  PL  46,  Figs.  14-16. 

Nova  Acta  Phys.  Med.  Ac.  Caes.  Leop.-Carol.  Nat.  Cur.  14^•  772,  pi.  43,  figs. 
6-20.  1829. 

Coenobia  of  8-16-32-61r-128  (generally  16-32)  cells,  with  small  lens- 
shaped  perforations  between  the  cells.  Interior  cells  more  or  less  rec- 
tangular, not  in  contact  with  one  another  in  the  central  portion  of  the 
side  walls.  Inner  half  of  marginal  cells  similar  to  interior  cells,  outer 
half  prolonged  into  two  short  truncate  processes.  Cell  wall  smooth. 
(Facultative  Planktont). 

Diam.  cells  11-21  /a. 

Balsam  (rrr).  Bear  (2)  (r),  Birch  Island  (rr),  Browns  (rr),  Catherine  (rr). 
Center  (r).  Clam  (rrr),  Cochrane  (rr).  Crawling  Stone  (r).  Deer  (rr),  Des 
Moines  (rrr),  Diamond  (rrr).  Eagle  (r),  Fishtrap  (rr).  Found  (rr),  Fowler 
(rr),  Helen  (1)  (rr).  High  (rr),  Kawaguesaga  (rr),  Kegonsa  (r).  Kitten  (r). 
Lac  la  Belle  (r),  Lindy  (rr).  Little  Bass  (2)  (rr),  Little  Bear  (r).  Little 
Crooked  (r).  Little  Rice  (2)  (rr).  Long  (3)  (rrr).  Lost  (rr),  Mendota  (sss), 
Mercer  (rr),  Meronk  (rrr),  Monona  (c),  Nagawicka  (rr),  Nancy  (sss),  Nica- 
boyne  (rrr).  North  Twin  (rr),  Oconomowoc  (rr),  Okauchee  (rr),  Pardee  (rr), 
Pokegama  (1)  (ss),  Pokegama  (2)  (rr).  Poor  Farm  (r).  Poplar  (rrr).  Round 
(1)  (r).  Round  (2)  (rr).  Sand  (4)  (sss),  Sishebogema  (rr).  Soft  (r).  South 
Turtle  (sss),  Taylor  (rr).  Tenderfoot  (r).  Tied  Canoe  (rrr).  Upper  Nemahbin 
(rr),  Waubesa  (ccc),  White  Sand  (rrr).  Wildcat  (sss).  Wild  Goose  (rrr), 
Winnebago  (ss),Wolf  (sss). 

In  many  cases  the  marginal  cells  of  this  species  and  the  varieties 
clathratum,  reticulatum  and  graeilUmum  have  a tuft  of  long  hyaline 
setae  at  the  apex  of  the  projections.  Their  function  is  to  give  buoyancy 
to  the  coenobe  when  living  under  pelagic  conditions.  Petersen  (Bot. 
Tids.  31:  161-176.  1911)  has  been  able  to  demonstrate  their  presence 
in  other  species  by  means  of  stains. 


var.  CLATHRATUM  (A.  Braun)  Lagerheim.  PL  47,  Pigs.  1-3. 
Ofvers.  Kgl.  Vet.-Ak.  Forh.  39,  No.  2:  56.  1882. 

Cells  more  deeply  emarginate  and  perforations  of  disc  larger.  (Fac- 
ultative Planktont). 

Diam.  cells  12-22  ft. 

Balsam  (rr),  Bear  (3)  (rr).  Bear  Trap  (rr),  Beaverdam  (sss).  Big  Butter- 
nut (rr),  Blake  (r).  Bloom  (rr).  Camp  (ss).  Catfish  (rr),  Catherine  (rr), 
Chetek  (s).  Cranberry  (rr).  East  (rrr).  Fish  (s).  Horseshoe  (1)  (rr).  Horse- 
shoe (2)  (rr).  Lac  du  Flambeau  (rrr).  Lac  la  Belle  (r).  Little  Bass  (2)  (sa). 
Little  Butternut  (r).  Little  Wood  (rrr).  Long  (1)  (rrr),  Loveless  (sss). 
Lower  Turtle  (r),  Mary  (r),  Mendota  (r).  Middle  McKenzie  (s).  Mud  (2)  (rr), 
Mud  (3)  (sss),  Nancy  (r),  Okauchee  (rrr).  Old  Taylors  (rrr),  Pokegama  (1) 
(r).  Rice  (1)  (ss).  Round  (2)  (rr),  Sand  (3)  (rr).  Sand  (4)  (r).  Spirit  (sss). 
Upper  Turtle  (sss),  Wapagossett  (rr).  White  Ash  (r). 


172 


WISCONSIN  PHYTOPLANKTON 


var.  RETicuLATUM  Lagerheim.  PI.  47,  Figs.  4-7. 
ofvers.  Kgl.  Vet.-Ak.  Forh.  39,  No.  2:  56,  pi.  2,  fig.  1.  1882. 

Perforations  of  coenobe  very  large,  oval.  Interior  cells  sub-cruciate 
to  H-shaped.  Sides  of  projections  of  marginal  cells  parallel,  projec- 
tions generally  terminating  in  a tuft  of  delicate  long  hyaline  setae. 
(Euplanktont  ?). 

Cells  10-20  fi  broad,  15-40  fi  long. 

Big  (rr),  Camp  (s),  Center  (s),  Clietek  (b),  Crab  (rr),  Hill  (rr),  Hooker 
(rr),  Horse  (sss),  Island  (sss),  Kawaguesaga  (rr),  Little  Bear  (rr).  Little 
Rice  (1)  (rr).  Lost  Bass  (r),  Loveless  (r),  Nancy  (r),  Paddock  (rr),  Palmer 
(r),  Pardee  (r).  Pine  (2)  (rrr),  Pokegama  (1)  (r),  Pokegama  (3)  (ss), 
Prairie  (ss).  Reserve  (rr).  Rice  (r),  St.  Croix  (sss),  Sisbebogema  (r).  South 
Turtle  (rr),  Tenderfoot  (rr),  Waubesa  (rr),  Whitefish  (rr),  Winnebago  (rr). 

var.  GRACiLLiMUM  W.  & G.  S.  West.  PI.  47,  Figs.  8-11 ; PI.  48,  Figs.  1-2. 
Jour,  of  Bot.  33:  52.  1895. 

Cells  very  narrow,  never  wider  than  the  processes.  Body  of  margi- 
nal cells  curved  outwards,  with  two  long,  somewhat  converging  processes 
that  have  parallel  or  slightly  convex  sides.  Interior  cells  like  those  of 
margin  but  with  somewhat  shorter  processes.  Perforations  of  coenobe 
very  large.  (Euplanktont). 

Cells  10-22  fjL  broad,  12-32  /a  long.  Diam.  16-celled  coenobia  65-140  /x. 

Clam  (rr).  Pine  Tree  (sss),  Travis  (r). 

The  perforations  of  the  coenobe  and  the  extension  of  the  processes 
are  the  greatest  in  this  variety.  The  varieties  clathratum,  reticvlatum, 
and  gracillimum  are  not  sharply  defined  and  it  is  possible,  taking  the 
collections  as  a whole,  to  arrange  a series  that  grades  almost  impercept- 
ibly from  the  typical  form  to  the  variety  gracillimum.  The  individuals 
from  any  one  lake,  however,  generally  vary  within  fairly  narrow  limits 
so  I feel  that  these  varieties  should  be  recognized  instead  of  putting 
them  in  one  collective  species  without  varieties. 


var.  ROTUNDATUM  Lucks.  PI.  46,  Fig.  17. 

Jahrb.  d.  Westpr.  Lehrervereins  f.  Naturk.  2-3:  31.  1907;  Nitardy,  Beih.  z. 
Bot.  Cent.  32=*:  pi.  9,  fig.  11.  1914. 

Projections  of  marginal  cells  markedly  convex  and  capitate  instead 
of  parallel.  (Tychoplanktont). 

Oconomowoc  (rrr).  Horseshoe  (1)  (rr). 


WISCONSIN  PHYTOPLANKTON 


173 


var.  coHAERENS  Bohlin.  PI.  48,  Figs.  3-4. 

Bih.  t.  Kgl.  Sv.  Vet.-Ak.  Handl.  23,  Afd.  3,  No.  7:  31,  pZ.  2,  fig,  1.  1897. 

Pediastrum  duplex  var.  reticulatum  forma  coJiaerens  (Bohlin)  Brunnthaler, 
in  Pascher,  D.  Siisswasserfl.  Deutschl.,  osterr.  u.  d.  Schw.  5^:  95,  fig.  57e.  1915. 

Coenobia  circular  to  oval,  of  16-32-64  cells,  with  median-sized  inter- 
cellular spaces.  Wall  of  cells  covered  with  short,  linear,  concentrically 
arranged  granules.  (Facultative  Planktont). 

Cells  12-22  fjL  broad ; 13-24  fi  long. 

Pine  Tree  (r). 

Pediastrum  biradiatum  Meyen.  PI.  48,  Figs.  5-8. 

Nova  Acta  Phys.-Med.  Ac.  Caes.-Leop.  Nat.  Cur.  14^:  773,  pi.  43,  figs.  21-22.  1829. 

Pediastrum  rotula  (Ehrenberg)  A.  Braun  emend.  Alg.  unicell.  101,  pi.  6, 
figs.  2-3,  5-7,  10,  12-14.  1855. 

Coenobia  of  4-8-16-32-64  cells,  with  medium  sized  openings  between 
cells.  Marginal  cells  in  contact  with  one  another  at  base  only,  with 
two  long  projections  that  are  dilate  and  incised  at  the  apex.  Interior 
cells  as  those  of  the  margin  but  apices  of  projections  neither  dilate  nor 
incised,  in  contact  with  other  cells  at  base  and  ends  of  projections  only. 
Cell  wall  smooth.  (Facultative  Planktont). 

Cells  10-22  broad,  15-30  fi  long.  Diam.  32-celled  coenobia  80-150  /x. 

Balsam  (rrr).  Bear  (3)  (rr),  Big  McKenzie  (rr),  Lac  du  Flambeau  (rr), 
Mud  (2)  (rr),  Nancy  (rrr),  Pokegama  (1)  (rrr),  Wolf  (rrr). 

This  species  resembles  P.  duplex  var.  reticulatum  in  the  perforation 
of  the  disc  but  differs  in  the  deep  incision  of  the  marginal  cell  projec- 
tions. Perfect  colonies  are  seldom  seen  since  apices  of  projections  of 
certain  interior  cells  are  free  and  have  the  same  dilation  and  incision 
that  is  found  in  the  marginal  cells.  The  number  of  ceUs  in  the  colony 
is  generally  stated  as  8-16-32  but  the  coenobia  in  the  plankton  of  Wis- 
consin lakes  are  32-  or  64-celled  except  in  very  rare  cases. 

Pediastrum  tetras  (Ehrenberg)  Ralfs.  PL  48,  Figs.  9-12. 

Ann.  & Mag.  of  Nat.  Hist.  14:  469,  pi.  12,  fig.  4.  1844. 

Coenobia  rectangular,  oval  or  circular;  without  perforations;  of 
4-8-16-32  (generally  4-8)  cells.  Outer  face  of  marginal  cells  with  a 
single  deep  linear  to  cuneate  incision,  the  halves  of  the  outer  face 
slightly  to  deeply  emarginate.  Interior  cells  with  a single  deep  linear 
incision  and  4-6  straight  sides.  Cell  wall  smooth.  (Tychoplanktont). 

Diam.  cells  8-15  /x. 

Blake  (rrr).  Browns  (rrr).  Chain  (rrr),  Chetek  (rr),  Cochrane  (rrr),  Hill- 
man (rrr).  Horse  (rrr).  Horseshoe  (2)  (rrr),  Kimball  (rrr),  Lindy  (rrr). 


174 


WISCONSIN  PHYTOPLANKTON 


Little  Doctor  (rr),  Mendota  (rrr),  Palmer  (rrr),  Pewaukee  (rrr),  Pine  (2) 
(rr),  Pokegama  (1)  (rr),  Poor  Farm  (rr),  Tied  Canoe  (rrr). 

The  four  projections  in  the  outer  face  of  marginal  cells  are  due  to  a 
deep  emargination  of  the  two  halves.  This,  coupled  with  the  deep  in- 
cision of  all  cells,  at  once  separates  the  species  from  others  of  the  genus. 
The  alga  does  not  thrive  under  plankton  conditions  although  it  is  com- 
mon in  ditches  and  ponds  of  the  state. 

var.  OBTUSATA  Raciborski. 

Akad.  Umiej.  w.  Krakowie  20:  32.  1889;  Printz,  Skr.  Vidensk.  i Kristiana 
Mat.-Naturv.  Kl.  1913S  No.  6:  78,  pi.  6,  fig.  153.  1914. 

Cells  larger  than  typical  form,  sometimes  expanded  at  base.  Halves 
of  outer  face  of  marginal  cells  entire  or  very  slightly  emarginate. 
( Tychoplanktont ) . 

Diam.  cells  14-18  p, ; length  18-22  p.. 

Beaverdam  (rrr). 

var.  TETRAODON  (Corda)  Hansgirg.  PI.  48,  Figs.  13-14;  PI.  49,  Figs.  1-2. 

Prodr.  d.  Algenfl.  v.  Bohmen  1:  112.  1888. 

Euastrum  tetraodon  Corda,  Almanach  de  Carlsbad  9:  238,  pi.  2,  fig.  9.  1839. 

Coenobia  generally  8-celled.  Incision  of  cells  deep,  and  with  projec- 
tions adjacent  to  incision  very  pronounced  on  marginal  cells.  (Facul- 
tative Planktont). 

Diam.  marginal  cells  8-15  ju,;  length  12-18  fi. 

Pine  Tree  (rr),  Travis  (r). 

There  is  no  question  that  my  figures  of  the  organism  are  identical 
with  the  one  that  Nitardy  (Beih.  Bot.  Cent.  32^ : 123,  pi.  5,  fig.  8.  1914) 
has  reproduced  from  Corda.  The  variety  is  sharply  defined  through 
the  greater  development  of  the  projections. 

EUASTROPSIS  Lagerheim  1894. 

Coenobia  free-floating,  2-celled.  Cells  flattened,  approximated  at  the 
bases,  distal  end  free  and  deeply  emarginate.  Chloroplast  single,  pari- 
etal, with  one  pyrenoid. 

Asexual  reproduction  by  division  of  cell  contents  into  2-4^8-16-32 
zoospores  which  are  extruded  in  a vesicle  and  on  becoming  quiescent 
join  in  pairs  to  form  the  characteristic  coenobe. 

Sexual  reproduction  unknown. 


WISCONSIN  PHYTOPLANKTON 


175 


Euastropsis  Richteri  (Schmidle)  Lagerheim.  PI.  49,  Fig.  3. 
Tromso  Museums  Aarshefter  17:  20,  pi.  1,  figs.  8-27.  1894. 

Cells  trapezoidal,  outer  face  deeply  emarginate.  (Tychoplanktont). 

Cells  4.5-25  /a  broad,  5-20  /x  long.  Coenobia  4.5-25  fi  broad,  10-40 
(I  long. 

Kegonsa  (rrr). 

It  is  quite  possible  to  mistake  2-celled  Pediastrum  colonies  for 
E.  Richteri,  but  since  such  Pediastrum  colonies  are  of  very  rare  occur- 
rence the  similarity  of  the  two  is  not  apt  to  lead  to  confusion. ' 

Family  PLAN 08P0R ACE AE. 

Cells  solitary  or  gregarious;  ovoid,  pyriform,  fusiform,  cylindrical, 
or  hemispherical ; epiphytic,  endophytic,  or  epizootic.  Cells  capable  of 
growth  but  incapable  of  division  after  their  formation.  Generally  with 
a single  chloroplast  with  one  or  more  pyrenoids. 

Asexual  reproduction  by  division  of  cell  contents  to  form  many  zoo- 
spores. 

Only  one  genus,  Characium,  is  found  in  the  plankton  of  the  state. 

CHARACIUM  A.  Braun  1849. 

Cells  sub-spherical,  ovoid,  pyriform,  fusiform,  or  cylindrical;  soli- 
tary or  gregarious;  epiphytic  or  epizootic;  generally  attached  to  sub- 
stratum by  a more  or  less  elongate  stipe,  rarely  sub-sessile.  Chloroplast 
parietal  and  laminate  to  cup-shaped  in  young  cells ; later  expanded  to 
fill  entire  cell : with  one  or  more  pyrenoids.  Cells  at  times  with  several 
chloroplasts. 

Asexual  reproduction  by  repeated  division  of  cell  contents  into  8-16- 
32-64-128  zoospores  that  are  liberated  through  a lateral  or  apical  pore. 
Zoospores  swarming  but  a short  time  and  then  coming  to  rest  on  sub- 
stratum and  developing  into  vegetative  cells. 

Microgametes  reported  but  doubtful. 

KEY  TO  THE  SPECIES. 


Epiphytic  upon  other  algae. 

Cells  ovoid C.  Stipitattjm 

Cells  lunate C.  Cubvatum 

Epizootic  upon  crustaceans. 

Apices  of  cells  rounded C.  Cylindbictjm 

Apices  of  cells  produced  into  a fine  seta. 

Stipe  simple C.  Limnetictjm 

Stipe  ending  in  filiform  rhizoids C.  Geachjpes 


176 


WISCONSIN  PHYTOPLANKTON 


Characium  stipitatum  (Bachmann)  Wille.  PL  49,  Figs.  4-7. 

in  Engler  & Prantl,  Nat.  Pflanzenfam.  V (Nachtr.);  45.  1909;  G.  M.  Smith, 
Bull.  Torr.  Bot.  Cl.  43:  472,  pi,  24,  figs.  4-6.  1916. 

Cells  spherical  to  pyriform,  with  a delicate  hyaline  stipe  somewhat 
longer  than  the  cell.  Chloroplast  single,  parietal,  cup-shaped,  always 
on  the  side  away  from  the  stipe;  pyrenoid  single.  Zoospores  broadly 
ovoid,  biciliate,  with  a cup-shaped  chloroplast  at  the  posterior  end. 
(Euplanktont). 

Epiphytic  upon  and  embedded  within  the  gelatinous  envelope  of 
Coelosphaerium  Naegelianwn  Unger. 

Cells  5-8  fx  broad.  Stipe  10-16  p.  long. 

Amicoy  (r).  Balsam  (rr),  Beartrap  (rr),  Beaverdam  (s),  Big  (rr),  Big 
McKenzie  (ss),  Clam  (ss),  Devils  (2)  (ss).  Horseshoe  (1)  (ss),  Horseshoe 
(2)  (rr),  Long  (2)  (ss),  Kawaguesaga  (ss).  North  Twin  (sss),  Pardee  (r). 
Pike  (rr),  Pokegama  (1)  (s),  Pokegama  (2)  (r).  Poplar  (rrr),  St.  Croix  (r). 
Sand  (4)  (rr),  Sishebogema  (rr). 

In  one  case  the  alga  was  found  upon  Oocystis  but  in  all  others  it  was 
inside  the  gelatinous  envelope  of  Coelosphaerium  Naegelianwn  Unger. 
When  the  alga  grows  upon  Coelosphaerium  the  colony  is  apt  to  be  in- 
fested with  50-100  individuals  as  a rule.  The  alga  was  originally  des- 
cribed as  a Chlamydomonas  species  but  since  the  sessile  phase  is  the 
dominant  one  of  the  life  cycle  it  is  better  placed  as  a Characium  species. 
Although  found  at  only  one  station  in  Europe  it  is  widely  distributed 
in  northern  Wisconsin. 

Characium  curvatum  G.  M.  Smith.  PI.  49,  Figs.  8-15. 

Trans.  Wis.  Acad.  Sci.,  Arts,  & Lett.  19^:  641,  pi.  11,  figs.  6-13.  1918. 

Cells  lunate  or  recurved,  with  acute  or  sub-acute  apices.  Stipe  hya- 
line, thick,  tubular  or  conical,  sometimes  irregular  in  outline.  Chloro- 
])last  single,  parietal,  laminate  to  cup-shaped;  with  or  without  a pyre- 
noid. ( Euplanktont) . 

Epiphytic  upon  Coelosphaerium  Naegelianum  Unger,  Bictyosphaer- 
ium  pulchellum  Wood,  and  Phaeococcus  planet onicus  W.  & G.  S.  West. 

Cells  3-6  /A  broad,  8-18  p long  (without  stipe),  13-22  /a  long  with 
stipe. 

Bear  (1)  (rr),  Birch  (2)  (cc).  Chain  (rr),  Chetac  (aa),  Chetek  (rr),  Clam 
(sss).  East  (rr),  Horseshoe  (1)  (ss),  Lindy  (rr).  Mud  (1)  (rr).  South  Crab 
(ss).  Wild  Goose  (rr). 

An  alga  that  resembles  C.  stipitatum  in  the  manner  of  growth  but 
one  which  is  found  upon  a wider  range  of  genera.  It  also  differs  in  the 
curved  cells  and  the  broader  stipe. 


WISCONSIN  PHYTOPLANKTON 


177 


Characium  cylindricum  Lambert.  PI.  49,  Pigs.  16-19. 
Rhodora  11:  70,  pi.  79,  figs.  1-2,  7-8,  10-13,  23-25.  1909. 

Cells  cylindrical,  with  rounded  apices,  base  tapering  slightly  into  a 
short  stipe  without  a basal  disc.  Chloroplasts  1-16,  parietal,  disciform 
to  laminate,  without  pyrenoids.  (Euplanktont). 

On  Diaphanosoma  hrachyura  and  Branchipus  vernalis. 

Cells  8-20  fjL  broad,  20-430  /a  long. 

Howey  (cc). 

- The  lack  of  a pyrenoid  suggests  Characiopsis  but  the  bright  green 
color  of  the  chloroplast  shows  that  the  alga  is  one  of  the  Chlorophyceae 
and  so  is  placed  among  Cho/racium  species.  Young  cells  contain  a sin- 
gle chloroplast  but  with  growth  there  is  an  increase  in  the  number  of 
chloroplasts  and  all  stages  between  cells  with  a single  chloroplast  and 
those  with  sixteen  may  be  found  on  the  same  crustacean.  Lambert 
holds  that  this  condition  is  a stage  in  the  division  into  zoospores  but 
in  my  opinion  it  is  the  normal  condition  of  the  adult  cell.  Another 
point  of  interest  is  the  position  of  the  alga  upon  the  host  since  it  is 
only  found  on  the  tail  of  the  crustacean. 


Characium  limneticum  Lemmermann.  PI.  49,  Figs.  25-29. 

Bot.  Not.  1903:  81,  pi.  3,  figs.  7-10.  1903. 

Cells  broadly  fusiform,  lunate,  rarely  straight;  apex  produced  into 
a single  delicate  hyaline  seta ; base  a delicate  stipe  without  basal  discs. 
1-8  parietal  band-shaped  chloroplasts,  each  containing  1-2  pyrenoids. 
(Euplanktont). 

Cells  5-14  /A  broad,  25-110  /a  long ; stipe  5-10  /a  long. 

On  Diaphanosoma  hrachyura. 

Boulder  (rr).  Browns  (rr),  Delavan  (rrr). 

Lemmermann  describes  the  chloroplast  as  single  but  reports  a divi- 
sion of  the  chloroplast  prior  to  division.  I have  found  that  in  all  nor- 
mal adult  cells  of  C.  limneticum,  C.  gracilipes,  and  C.  cylindricum  there 
is  more  than  one  chloroplast. 

The  species  is  very  closely  related  to  C.  gracilipes  but  is  much 
smaller,  proportionally  broader,  and  has  a simple  stipe.  It  is  very 
probable  that  Raphidium  longissimum  var.  septatum  Chodat  {Ankistro- 
desmus  longissimum  var.  septatum  (Chodat)  Brunnthaler)  is  a cell  of 
C.  limneticum  broken  off  from  the  crustacean  during  collection. 


12 


178 


WISCONSIN  PHYTOPLANKTON 


Characium  gracilipes  Lambert.  PI.  49,  Figs.  20-24. 

Rhodora  11:  65,  pi.  79,  figs.  3-6,  9,  14-22.  1909. 

Cells  straight  or  curved  with  the  median  portion  fusiform;  apex 
tapering  into  a long  seta  and  base  attenuated  to  a filiform  stipe.  Chloro- 
plast  parietal,  band-shaped,  1-32  per  cell;  with  one  pyrenoid  in  each 
chloroplast.  ( Euplanktont) . 

On  Diaphanosoma  hrachyura. 

Cells  5-14  /X  broad,  70-480  /x  long. 

Howey  (cc). 

This  alga  was  found  on  the  same  organism  and  at  the  same  time  as 
C.  cylindricum.  It  was  confined  to  the  forward  appendages  while 
C.  cylindricum  was  found  at  the  tail  only. 

Order  ULOTMCHALES. 

Cells  usually  in  a simple  or  branched  thallus,  rarely  forming  disci- 
form thalli  one  cell  in  thickness.  Thallus  generally  attached,  rarely 
free-floating;  naked,  or  enclosed  by  a tough  and  leathery  or  copious 
and  gelatinous,  homogeneous  or  lamellated  envelope.  Cells  generally 
with  a single  parietal  laminate  to  cup-shaped  chloroplast  with  one  or 
more  pyrenoids.  Cell  shape  usually  cylindrical  with  flattened  ends, 
rarely  cylindrical  with  rounded  ends,  spherical  or  cubical. 

Asexual  reproduction  by  vegetative  cell  division,  by  a division  of 
vegetative  or  special  cells  to  form  2-16  bi-  or  tetraciliate  zoospores,  and 
by  aplanospores. 

Sexual  reproduction  either  isogamous  by  a division  of  ceU  contents 
to  form  bi-  or  tetraciliate  zoogametes ; or  heterogamous  by  the  fusion  of 
tetraciliate  zoogametes  of  different  size  or  the  union  of  large  non-motile 
oospheres  and  small  biciliate  antherozoids. 


KEY  TO  THE  FAMILIES. 

Cells  united  to  form  simple  filaments Ulotbjchaoeab 

Cells  united  to  form  branching  filaments. 

Sexual  reproduction  by  isogamoua  zoogametes Chaetophoraceae 

Sexual  reproduction  by  heterogamous  zoogametes Aphanochaetaceae 


Family  ULOTRICHACEAE. 

Cells  united  to  form  simple  free-floating  or  sessile  filaments  which 
are  enclosed  at  times  by  a copious,  hyaline,  homogeneous  or  radially 
fibrillar,  gelatinous  envelope.  Cell  shape  spherical  to  cylindrical  with 
rounded  or  flattened  ends.  Walls  of  cells  delicate  or  thick,  homogen- 


WISCONSIN  PHYTOPLANKTON 


179 


ecus  or  lamellated.  Cells  containing  a nucleus  and  one  parietal,  lami- 
nate or  cup-shaped  chloroplast  with  one  or  more  pyrenoids. 

Asexual  reproduction  by  vegetative  cell  division,  aplanospores  or 
biciliate  zoospores. 

Sexual  reproduction  isogamous,  by  a fusion  of  bi-  or  tetraciliate  zoo- 
gametes. 

ULOTHRIX  Kiitzing  1833. 

Filaments  simple,  free-floating  or  with  the  basal  cell  modified  to  form 
a hold-fast.  Cells  cylindrical,  with  flattened  end  walls,  united  to  form 
simple  filaments  that  are  the  same  diameter  throughout.  Wall  of  cells 
delicate  or  thick,  homogeneous  or  lamellated,  without  a gelatinous  outer 
layer.  Chloroplast  single,  parietal,  laminate,  with  one  or  more  pyre- 
noids. Cells  uninucleate. 

Asexual  reproduction  by  the  division  of  cell  contents  to  form  1-32  . 
aplanospores  and  bi-  or  tetraciliate  zoospores. 

Sexual  reproduction  isogamous,  by  a fusion  of  biciliate  zoogametes. 

KEY  TO  THE  SPECIES. 


Filaments  11-45  fi  in  diameter U.  Zonata 

Filaments  5-7  in  diameter U.  Subconsteicta 


Ulothrix  zonata  (Weber  & Mohr)  Kiitzing.  PL  50,  Fig.  6. 
Flora  16:  519.  1833;  Hazen,  Mem.  Torr.  Bot.  Cl.  11:  147,  pi.  20,  figs.  1-4.  1902. 

Filaments  attached  or  free-floating  and  forming  greenish  masses. 
Cells  disciform  to  cylindrical,  % to  V/2  times  as  long  as  broad.  End 
walls  of  cells  straight,  side  walls  straiglit  or  slightly  convex  in  older 
cells.  Chloroplast  forming  a broad  or  narrow  pariccal  annular  girdle 
containing  several  pyrenoids.  Wall  of  cell  thick,  generally  homo- 
geneous but  at  times  lamellated  in  structure.  (Tychoplanktont). 

Mature  cells  11-45  p in  diameter. 

Mendota  (rrr). 

Ulothrix  subconstricta  G.  S.  West.  PL  50,  Figs.  4r-5. 

Jour,  of  Bot.  53  : 82,  figs.  6a-6c.  1915. 

Filaments  free-floating,  narrow,  slightly  constricted  at  cross  walls  of 
cells,  with  or  without  a homogeneous  gelatinous  envelope.  Cells  elon- 
gate, 2-6  times  as  long  as  broad,  slightly  inflated  at  the  poles.  Chloro- 
plast single,  parietal,  laminate,  with  irregular  edges  and  occupying 
the  median  two  thirds  of  the  cell.  With  or  without  1-2  pyrenoids. 
Cell  wall  very  delicate.  (Facultative  Planktont). 


180 


WISCONSIN  PHYTOPLANKTON 


Cells  5.7-9  broad. 

The  specimens  that  I have  found  in  our  lakes  differ  somewhat  from 
those  described  by  West  since  the  cells  are  not  slightly  dilate  at  the 
poles  and  the  chloroplasts  usually  contain  pyrenoids.  The  Wisconsin 
organism  does  not  seem  sufficiently  differentiated,  however,  to  warrant 
the  description  of  a new  variety  or  species.  This  alga  is  of  particular 
interest  since  it  is  the  only  one  of  the  order  which  has  become  established 
as  a true  member  of  the  plankton. 

Family  CHAETOPHORACEAE, 

Cells  united  to  form  branching  filamentous,  discoidal  or  parenchyma- 
tous thalli.  Branches  of  thallus  generally  attenuated  at  apices  and 
sometimes  ending  in  long  hair-like  processes.  Thallus  naked  or  en- 
closed in  a copious,  hyaline,  homogeneous,  gelatinous  envelope.  Cell 
shape  ordinarily  cylindrical  with  flattened  ends.  Chloroplast  single, 
parietal  and  laminate  to  girdle-shaped;  with  one  or  more  pyrenoids. 
Nucleus  single. 

Asexual  reproduction  by  aplanospores  and  bi-  or  tetraciliate  zoo- 
spores. 

Sexual  reproduction  isogamous,  by  a fusion  of  biciliate  zoogametes. 

STIGEOCLONIUM  Kiitzing  1843. 

Thallus  free-floating  or  attached,  with  branches  scattered  and  not 
arising  in  dense  tufts.  Thallus  without  an  appreciable  difference  in 
size  between  the  main  stem  and  minor  branches ; covered  with  a homo- 
geneous, hyaline,  gelatinous  envelope.  Cells  cylindrical  to  disciform, 
gradually  decreasing  in  diameter  towards  the  apex  and  with  terminal 
cells  conical  or  elongated  to  hair-like  unseptate  processes.  Chloroplast 
single,  parietal ; gridle-shaped  and  filling  median  portion  of  older  cells ; 
completely  filling  younger  cells.  Each  chloroplast  generally  containing 
several  pyrenoids. 

Asexual  reproduction  by  aplanospores  and  tetraciliate  zoospores. 
Sexual  reproduction  isogamous,  by  the  fusion  of  biciliate  zoogametes. 

Stigeoclonium  lubricum  (Dillwyn)  Kiitzing.  PI.  50,  Fig.  7. 
Phycol.  germ.  189.  1845. 

Myxonema  liTbricum  (Dillw.)  Fries.  Hazen,  Mem.  Torr.  Bot.  Cl.  11:  195, 
p/.  28,  Ms.  1-2.  1902. 

Filaments  forming  dark  green  tufts  up  to  30  cm.  long.  Filaments 
much  branched  and  branches  usually  opposite,  rarely  single.  Cells  of 
main  filament  at  base  of  branches  sub-spherical,  shorter  than  other  cells. 


WISCONSIN  PHYTOPLANKTON 


181 


Branehlets  abundant,  opposite,  scattered  in  basal  portion,  dense  in  dis- 
tal, only  slightly  narrower  than  the  branch  from  which  they  arise  and 
with  terminal  cell  conical  or  setiferous.  Lower  cells  of  main  branch 
swollen,  %-4  times  as  long  as  broad,  with  a girdle-like  chloroplast  in 
median  portion.  (Tychoplanktont). 

Main  branches  14-16.5  fx  broad;  branehlets  6-7  fx  broad. 

Mendota  (rrr),  Wild  Goose  (rrr). 


Family  APHANOCHAETACEAE. 

Thallus  epiphytic,  generally  upon  other  algae,  creeping  in  habit  and 
composed  of  simple  or  irregularly  branching  filaments  that  taper  from 
the  center  to  short,  narrow  terminal  cells  that  do  not  end  in  terminal 
setae.  Central  cells  of  filament  spherical  to  spherical-cylindrical ; those 
towards  the  end  cylindrical  with  straight  or  convex  sides;  terminal 
cells  conical.  Cells  generally  bearing  one  or  more  long,  hyaline,  un- 
septate  setae  with  swollen  bases.  Chloropast  parietal,  completely  fill- 
ing the  cell,  or  gridle-like  and  in  the  median  portion;  generally  with 
more  than  one  pyrenoid. 

Asexual  reproduction  by  tetraciliate  zoospores  or  aplanospores. 

Sexual  reproduction  heterogamous,  by  the  fusion  of  tetraciliate  zoo- 
gametes that  are  markedly  different  in  size. 

The  family  contains  the  single  genus  Aphanochaete  whose  characters 
are  those  of  the  family. 


Aphanochaete  vermiculoides  WoUe.  PI.  50,  Fig.  8. 

Freshw.  algae  of  U.  S.  119,  pi.  105,  figs.  9-10.  1887. 

Herposteiron  hyalothecae  Hansgirg,  G.  M.  Smitli,  Trans.  Wis.  Acad.  Sci., 
Arts,  & Lett.  18^:  560.  1916. 

Filaments  but  slightly  branched  and  confined  to  the  peripheral  por- 
tion and  twisted  around  or  arched  from  the  gelatinous  envelope  of 
liyalotJieca  filaments.  Cells  cylindrical,  with  straight  or  convex  sides 
and  containing  a single  chloroplast  with  1-A  pyrenoids.  Setae  very 
sparse,  rarely  more  than  five  on  any  filament.  (Tychoplanktont). 

Cells  4^6  [I  broad ; 5-12  p,  long. 

Beaverdam  (rr). 

All  other  species  of  the  genus  grow  directly  upon  the  cells  of  the 
substratum  but  the  wide  gelatinous  envelope  of  the  Hyalotheca  is  in 
this  case  sufficiently  firm  to  support  the  Aphanochaete.  The  alga  has 
the  appearance  of  an  arching  worm  crawling  along  the  filament. 


182 


WISCONSIN  PHYTOPLANKTON 


Order  SIPHONOCLADIALES. 

Cells  multinucleate,  generally  cylindrical  and  united  to  form  simple 
or  branched  thalli  that  are,  at  times,  quite  complicated  in  structure. 
Chloroplasts  disciform,  parietal  and  numerous,  or  united  by  strands 
to  form  a single  reticulate  structure.  Pyrenoids  generally  present. 

Asexual  reproduction  by  zoospores  and  aplanospores. 

Sexual  reproduction  isogamous  by  means  of  zoogametes;  or  heter- 
ogamous  by  large  non-motile  oospheres  and  small  motile  antherozoids. 

The  order  is  largely  marine  and  only  one  representative,  CladopJim'a, 
has  been  found  in  the  plankton. 

Family  CLADOPHORACEAE. 

Filaments  generally  sessile,  simple  or  branched,  with  septations  be- 
tween the  cells  complete.  Walls  of  cells  generally  heavy,  homogeneous 
or  lamellose,  without  a gelatinous  envelope.  Cells  with  numerous 
parietal  disciform  chloroplasts  or  a single  reticulate  chloroplast ; multi- 
nucleate ; with  a single  large  central  vacuole. 

Asexual  reproduction  by  zoospores  and  akinetes. 

Sexual  reproduction  isogamous,  by  means  of  zoogametes. 

CLADOPHORA  Kiitzing  1843. 

Filaments  branched,  with  the  component  cells  in  a single  linear  series ; 
lateral  branches  arising  at  distal  part  of  main  branch  cells  and  gener- 
ally with  an  abundantly  developed  system  of  branching.  Growth  of 
filaments  confined  to  the  apical  region.  Cells  cylindrical,  several  times 
as  long  as  broad;  multinucleate;  with  numerous  parietal  disciform 
chloroplasts  or  the  chloroplasts  united  by  processes  to  form  a single 
reticulate  chloroplast;  pyrenoids  numerous. 

Asexual  reproduction  by  the  formation  of  many  biciliate  zoospores  in 
any  cell  of  the  filament. 

Sexual  reproduction  isogamous,  by  means  of  biciliate  zoogametes. 


Cladophora  glomerata  (L.)  Kiitzing.  PI.  50,  Figs.  1-3. 

Phycol.  gener.  266.  1843;  Collins,  Tufts  Coll.  Studies  2:  350,  pi.  13,  fig-  124. 
1909. 

Branching  of  filaments  fairly  dense  in  lower  portion  and  very  dense 
at  the  apex.  Ultimate  branchlets  containing  several  cells,  straight  or 
slightly  incurved,  with  ends  rounded  but  not  markedly  attenuated. 
Cells  of  main  branches  6-7  times  as  long  as  broad,  3-6  times  as  broad 


WISCONSIN  PHYTOPLANKTON 


183 


as  branchlets.  Zoospore  formation  confined  to  terminal  and  subtermi- 
nal cells.  (Tychoplanktont). 

Diam.  main  cells  75-100  />t,  branchlets  35-50  fi. 

Mendota  (rr). 

Division  AKONTAE. 

Cells  solitary  or  in  filaments,  variously  shaped,  with  one  or  more 
grass-green  chloroplasts  that  usually  contain  more  than  one  pyrenoid. 

Asexual  reproduction  ordinarily  by  vegetative  cell  division,  rarely  by 
aplanospores,  never  by  zoospores. 

Sexual  reproduetion  isogamous,  always  by  aplanogametes,  never  by 
ciliate  zoogametes. 

The  lack  of  cilia  in  every  type  of  reproduction  is  the  great  character- 
istic of  the  division.  It  includes  but  one  order,  the  Conjugates,  which 
forms  a very  homogeneous  though  diverse  group. 

Order  CONJUGALES. 

Cells  solitary  or  in  simple  filaments;  cell  shape  various,  cylindrical 
without  median  constrictions  or  bilaterally  symmetrical  and  usually 
with  a median  constriction  dividing  the  cell  into  two  symmetrical  halves. 
Cell  wall  smooth  or  variously  ornamented,  with  an  inner  firm  portion 
and  an  outer  gelatinous  portion  that  is  very  copious  at  times.  Chloro- 
plasts 1-8,  variously  shaped,  axial  or  parietal,  with  one  to  several  pyre- 
noids.  Nucleus  single,  at  the  center  of  the  cell. 

Asexual  reproduction  by  vegetative  cell  division  or  aplanospores. 

Sexual  reproduction  isogamous,  by  aplanogametes. 

KEY  TO  THE  FAMILIES. 


Cells  cylindrical,  without  a median  constriction,  united  to 

form  simple  filaments Zygnemaceae 

Cells  solitary  or  in  filaments,  divided  into  two  symmetri- 
cal halves,  generally  with  a median  constriction Desmidiaceae 


(See  Fart  II) 


Family  ZYGNEMACEAE. 

Cells  always  cylindrical,  with  ends  flattened  or  replicate,  serially 
arranged  to  form  simple  filaments  that  occasionally  have  simple  lateral 
outgrowths.  Filaments  generally  free-floating  though  at  times  attached 
by  a modification  of  terminal  cell  into  a basal  cell  with  short  rhizoidal 
processes.  Wall  of  cell  firm,  homogeneous,  with  a narrow  or  copious, 
homogeneous  or  radially  fibrillar,  gelatinous  covering.  Cell  contents 
consisting  of  a single  nucleus,  and  one  to  several  chloroplasts  that  are 


184 


WISCONSIN  PHYTOPLANKTON 


either  stellate  or  laminate  and  axial  or  parietal.  Chloroplasts  with  one 
to  many  pyrenoids. 

Asexual  reproduction  by  vegetative  cell  division  or  metamorphosis 
of  cell  contents  into  a single  large  aplanospore. 

Sexual  reproduction  isogamous,  by  metamorphosis  of  all  or  a part 
of  the  cell  contents  into  an  aplanogamete  which  fuses  with  an  aplano- 
gamete  from  the  same  or  another  filament.  Zygote  with  2-3  layers, 
sometimes  germinating  immediately  but  usually  after  a period  of  rest. 

KEY  TO  THE  GENERA. 


Chloroplast  stellate Zygnema 

Chloroplast  a longitudinal  band. 

Chloroplast  axial Mougeotia 

Chloroplast  parietal Spieogyea 


MOUGEOTIA  C.  A.  Agardh  1824. 

Cells  cylindrical,  generally  several  times  as  long  as  broad.  Chloro- 
plast single,  forming  an  axial  plate  extending  the  whole  length  of  the 
cell  and  generally  with  several  pyrenoids. 

Conjugation  generally  scalariform  and  with  the  zygote  formed  in  the 
conjugation  tube.  Zygote  at  times  occupying  the  median  portion  of 
male  and  female  gametangia  as  well  as  conjugation  tube.  Wall  of 
zygote  of  two  layers  the  inner  smooth,  the  outer  smooth  or  sculptured, 
hyaline  or  colored. 

Mougeotia  viridis  (Kutzing)  Wittrock.  PI.  51,  Fig.  1. 

Bih.  Kgl.  Sv.  Vet.-Ak.  Handl.  1,  No.  1:  39.  1872. 

Staurospermum  viride  Kutzing.  Cooke,  Brit.  Freshw.  Algae  107,  pi.  44, 
figs.  2a-2c.  1882. 

Cells  4-10  times  as  long  as  broad.  Zygospores  normally  bounded  by 
four  cells,  quadrangular,  with  concave  sides  and  truncate  corners. 
( Tychoplanktont) . 

Cells  6-8  fi  broad.  Zygotes  22-32  p,  broad. 

Okauchee  (rrr). 

ZYGNEMA  C.  A.  Agardh  1817. 

Cells  cylindrical,  rarely  more  than  twice  as  broad  as  long.  Filaments 
with  a terminal  cell  at  times  modified  to  form  a holdfast.  Cells  with 
one  nucleus  and  two  axial  stellate  chloroplasts  each  of  which  contain 
a single  pyrenoid.  Conjugation  lateral  or  scalariform,  with  a forma- 
tion of  zygospores  in  the  conjugation  tube  or  the  gametangia.  Zygotes 
ipherical  to  ellipsoid,  wall  with  three  layers. 


WISCONSIN  PHYTOPLANKTON 


185 


Zygnema  pectinatum  (Vauclier)  C.  A.  Agardh.  PI.  51,  Fig.  2. 

Synop.  algarum  Scand.  102.  1817;  DeBary,  Unters.  u.  d.  Fam.  d.  Conjugaten. 
77,  pi,  1,  figs.  15-19.  1858. 

Vegetative  cells  1-3  times  as  broad  as  long.  Zygospore  formed  in 
conjugation  tube,  with  rounded  ends.  Middle  layer  of  zygote  wall 
brown  and  scrobiculate.  (Tychoplanktont). 

Vegetative  cells  30-40  fi  broad.  Zygote  35-40  fx  broad. 

Oconomowoc  (rrr). 


SPIROGYRA  Link  1820. 

Cells  cylindrical,  with  end  walls  a flat  plane  or  replicate;  united  to 
form  simple  filaments  that  may  be  attached  by  a modification  of  the 
terminal  cell  into  holdfasts.  Length  of  cells  slightly  greater  than  to 
several  times  the  breadth.  Chloroplasts  one  to  several,  parietal,  in 
long  ribbons  that  extend  from  end  to  end  in  the  cell  and  generally 
make  several  spiral  turns.  Nucleus  single,  moored  in  the  center  of  the 
central  vacuole  by  cytoplasmic  strands  running  to  the  pyrenoids.  Chlor- 
oplasts wdth  several  pyrenoids  that  are  generally  in  a single  median  row. 

Conjugation  scalariform  or  lateral,  with  zygote  formation  in  game- 
tangia  and  never  in  the  tube.  Zygote  spherical,  ellipsoid,  or  cylindri- 
cal with  rounded  ends.  Middle  layer  of  zygote  hyaline  or  colored, 
smC'Oth  or  sculptured. 

Spirogyra  porticalis  (Muller)  Cleve.  PI.  51,  Fig.  3. 

Nova  Acta  Reg.  Soc.  Sci.  Upsaliensis  3,  Ser.,  6:  No.  11,  22,  pi.  5,  figs.  8-13. 
1868. 

Length  of  vegetative  cells  2-6  times  the  breadth.  Cells  with  plane 
cross  walls  and  containing  a single  chloroplast  that  makes  3-5  turns  and 
contains  numerous  conspicuous  pyrenoids.  Gametangia  but  little  swol- 
len when  zygospore  is  mature.  Zygospores  broadly  ovoid  to  sub-cylin- 
drical, with  a yellow  membrane  when  mature.  (Tychoplanktont). 

Diam.  cells  30-50  fi.  Diam.  zygospores  40-50  fx. 


Mendota  (rrr). 


1S6 


WISCONSIN  PHYTOPLANKTON 


PLATE  1. 

Page 

Fig.  1.  Chroococcus  minutus  (x  825) 28 

Fig.  2.  Chroococcus  dispersus  (x  825) 28 

Fig.  3.  Chroococcus  dispersus  var.  minor  (x  825) 28 

Fig.  4.  Chroococcus  limneticus  (x  825) 29 

Fig.  5.  Chroococcus  limneticus  var.  suhsalsus  (x  825) 29 

Fig.  6.  Chroococcus  limneticus  var.  carneus  (x  825) 30 

Fig.  7.  Chroococcus  limneticus  var.  distans  (x  825) 30 

Fig.  8.  Chroococcus  limneticus  var.  elegans  (x  *825) 30 

Fig.  9.  Chroococcus  turgidus  (x  1000) 31 


WISCONSIN  SURVEY 


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WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  2 


1 


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187 


PLATE  2. 

Page 

Fig.  1.  CUroococcus  giganteus  (x  825) 30 

Fig.  2.  Merismopedia  tenuissima  (x  1000) 33 

Fig.  3.  Merismopedia  punctata  (x  1000) 33 

Fig.  4.  Merismopedia  glauca  (x  1000) 32 

Fig.  5.  Merismopedia  elegans  (x  1000) 32 

Fig.  6.  Merismopedia  elegans  var.  major  (x  1000) 32 

Fig.  7.  Aphanocapsa  delicatissima  (x  1000) 41 

Fig.  8.  Aphanocapsa  elachista  var.  conferta.  (x  1000) 42 

Fig.  9.  Aphanocapsa  pulchra  (x  825) 42 

Fig.  10.  Aphanocapsa  endophytica  (x  1000) 42 


188 


WISCONSIN  PHYTOPLANKTON 


PLATE  3. 

Page 

Fig.  1.  Aphanocapsa  Grevillei  (x  825) 43 

Pig.  2.  Aphanocapsa  rivularis  (x  825) 43 

Fig.  3.  Aphanocapsa  elachista  var.  planctonica  (x  1000) 42 

Pigs.  4-5.  Coelosphaerium  Kuetzingianum  (x  825) 34 

Fig.  6.  Coelosphaerium  Naegelianum  (x  825) 35 

Fig.  7.  Coelosphaerium  duhium  (x  825) 35 


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PLATE  4. 

Page 

Fig.  1.  Coelosphaerium  Naegelianum  (x  825) 35 

Figs,  2-3.  Gomphosphaeria  aponina  (x  825) 37 

Fig.  4.  Gomphosphaeria  aponina  var.  cordiformis  (x  825) 37 

Fig.  5.  Gomphosphaeria  lacustris  (x  825) 36 

Fig.  6.  Microcystis  aeruginosa  var.  'major  (x  825) 40 


190 


WISCONSIN  PHYTOPLANKTON 


PLATE  5. 

Page 

Figs.  1-2.  Microcystis  aeruginosa  (Pig.  1,  x 825;  fig.  2,  x 180 39 

Fig.  3.  Microcystis  fios-aquae  (x  825) 39 

Fig.  4.  Microcystis  incerta  (x  825) 40 

Fig.  5.  ApTianothece  prasina  (x  825) 45 

Fig.  6.  Aphanothece  nidulans  var.  endophytica  (x  1000) 44 


WISCONSIN  SURVEY 


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PLATE  6. 

Page 

Fig.  1.  Aphanothece  nidulans  (x  1000) 44 

Fig.  2.  Aphanothece  stagnina  (x  825) 45 

Fig.  3.  Aphanothece  clathrata  (x  1000) 44 

Fig.  4.  Rhahdoderma  linear e (x  1000) 47 

Fig.  5.  Gloeothece  linearis  (x  1000)  46 

Fig.  6.  Gloeothece  linearis  var.  composita  (x  1000) v 46 

Fig.  7.  Dactylococcopsis  raphidioides  (x  825) 47 

Figs.  8-10.  Dactylococcopsis  acicularis  (x  1000) 48 


192 


WISCONSIN  PHYTOPLANKTON 


PLATE  7. 

Page 

Fig.  1.  SpiruUna  major  (x  1000) 50 

Fig.  2.  SpiruUna  princeps  (x  1000) 50 

Figs.  3-5.  Oscillatoria  proUfica  (x  825) 51 

Fig.  6.  Oscillatoria  tenuis  (x  825) 52 

Figs.  7-8.  Oscillatoria  tenuis  var.  tergestina  (x  825) 52 

Figs.  9-11.  Lyngbya  limnetica  (x  1000) 52 

Figs.  12-13.  Lyngdya  contorta  (x  1000) 53 

Figs.  14-15.  Lyngdya  Birgei  (x  825) 54 


WISCONSIN  SURVEY 


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193 


PLATE  8. 


Fig.  1.  Trichodesmium  lacustre  (x  1000) 

Fig.  2.  Anahaena  plantonica  (x  825) 

Fig.  3.  Anahaena  Bornetiana  (x  825) 

Figs.  4-5.  Anahaena  Levanderi  (x  825) 

Fig.  6.  Anahaena  macrospora  var.  rohusta  (x  825) . 

Fig.  7.  Anahaena  a3'^is  (x  825) 

Fig.  8.  Anahaena  limnetica  (x  825) 

Figs.  9-10.  Anahaena  augstumalis  var.  marcMca  (x  825) 

13 


Page 

54 

56 
58 
58 

57 
57 

57 

58 


194 


WISCONSIN  PHYTOPLANKTON 


PLATE  9. 

Page 

Figs.  l-i3.  Anahaena  spiroides  var.  crassa  (Pig.  1,  x 825,  figs.  2~3,  x 400)  59 

Figs.  4-5.  Anahaena  circinalis  (Fig.  4,  x 825,  fig.  5,  x 400) 59 

Fig.  6.  Anahaena  circinalis  var.  mao'ospora  (x  825) 60 


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195 


PJLATE  10. 

Page 

Fig.  1.  Anabaena  circinalis  var.  macrospora  (x  400) 60 

Figs.  2-4.  Anabaena  flos-aquae  (Figs.  2-3,  x 825;  fig.  4,  x 400) 60 

Figs.  5-7.  Anabaena  fios-aquae  var.  Treleasii  (x  825) 60 

Fig.  8.  Anabaena  Lemmermanni  (x  825) 61 


196 


WISCONSIN  PHYTOPLANKTON 


PLATE  11. 

Page 

Fig.  1.  Anahaena  Lemmermanni  (x  400) 61 

Figs.  2-4.  Aphanizomenon  flos-aquae  (Fig.  2,  x 400;  figs.  3-4,  x 1000)..  61 

Figs.  5-6.  OloeotricMa  ecTiinulata  (x  400) 63 


WISCONSIN  SURVEY 


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WISCONSIN  PHYTOPLANKTON  197 


PLATE  12. 

Page 

Fig.  1.  ChrysamoeM  radians  (x  1000) 67 

Pig.  2.  Mallomonas  producta  (x  500) 68 

Fig.  3.  Mallomonas  producta  var.  marchica  (x  500) 68 

Fig.  4.  Mallomonas  alpina  (x  500) 68 

Fig.  5.  Mallomonas  tonsurata  (x  500) 68 

Fig.  6.  Mallomonas  caudata  (x  500) 69 

Pigs.  7-8.  Chrysosphaerella  longispina  (Fig.  7,  x 400;  fig.  8,  x 1000)..  69 

Pigs.  9-10.  Synura  uvella  (Pig.  9,  x 1000,  fig.  10,  x 400) 70 


198 


WISCONSIN  PHYTOPLANKTON 


PLATE  13. 

Page 

Figs.  1-4.  Uroglenopsis  americana  (Fig.  1,  x 400;  figs.  2-4,  x 1000) ....  71 

Figs.  5-6.  Dinohryon  caldformis  (x  1000) 73 

Figs.  7-9.  DinoJ)ry on  tabellariae  (x  1000) 73 

Fig.  10.  Dinolryon  davaricum  (x  400) 73 

Fig.  11.  Dinohryon  stipitatum  (x  400) 74 

Fig.  12.  Dinohryon  sociale  (x  400) 74 

Fig.  13.  Dinohryon  setularia  (x  400) 74 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  13 


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PLATE  14. 

Page 

Pig.  1.  DinoJ)ryon  setularia  (x  400) 74 

Fig.  2.  Dinobryon  divergens  (x  400) 75 

Figs.  3-4.  Hyalobryon  mucicola  (x  1000) 75 

Pig.  5.  Phaeococcus  plantonicus  (x  1000) 76 

Fig.  6.  Rhizochrysis  limnetica  (x  400) 77 

Figs.  7-8.  Chrysidiastrum  catenulatum  (Fig.  7,  x 500,  fig.  8,  x 1000)...  78 


200 


WISCONSIN  PHYTOPLANKTON 


PLATE  15. 

Page 

Pigs.  1-3.  Chlorochromonas  minuta  (x  1000) 80 

Fig.  4.  Peroniella  planctonica  (x  1000) 81 

Fig.  5.  Botryococcus  Braunii  (x  400) 84 

Figs.  6-7.  Botryococcus  protuberans  var.  minor  (Fig.  6 x 500,  fig.  7 x 

1000)  85 

Fig.  8.  Botryococcus  sudeticus  (x  400) 83 

Fig.  9.  Chlorobotrys  limneticus  (x  1000) 82 

Fig.  10.  Chlorolotrys  regularis  (x  1000) 82 

Fig.  11.  Ophiocytium  parvulum  (x  1000) 86 

Figs.  12-13.  Ophiocytium  capitatum  (x  1000) 86 

Figs.  14-16.  Ophiocytium  capitatum  var.  longispinum  (x  1000) 86 

Figs.  17-18.  Trihonema  minus  (x  1000) 87 


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PLATE  16. 

Page 

Fig.  1.  Carteria  cordiformis  (x  1000) 92 

Figs.  2-4.  Carteria  Elehsii  (x  1000) 93 

Figs.  5-7.  Chlamydomonas  dinohryoni  (x  1000) 91 

Pig.  8.  Chlamydomonas  glohosa  (x  1000) 90 

Figs.  9-10.  Chlamydomonas  Snowii  (x  1000) 91 

Figs.  11-13.  Chlamydomonas  epiphytica  (x  1000) - 91 

Figs.  14-15.  Gonium  pectorale  (x  500) 94 

Figs.  16-17.  Pandorina  morum  (x  400) 95 


202 


WISCONSIN  PHYTOPLANKTON 


PLATE  17. 


Figs.  1-3.  Pleodorina  calif ornica  (x  400) , 


Page 

97 


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BULLETIN  57.  PLATE  17 


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BULLETIN  57,  PLATE  18 


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203 


PLATE  18. 

Page 

Pig.  1.  Yolvox  mononae  (x  266) 99 

Fig.  2.  Yolvox  aureus  (x  266) 98 

Figs.  3-5.  Yolvox  fflodator  (x  266) 98 


204 


WISCONSIN  PHYTOPLANKTON 


PLATE  19. 

Page 

Pig.  1.  Eudorina  elegans  (x  500) 96 

Fig.  2.  Gloeocystis  gigas  (x  1000) 101 

Figs.  3-4.  Sphaerocystis  Schroeteri  (x  1000) 101 

Figs.  5-6.  Tetraspora  lacustris  (x  500) 102 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  19 


SMITH- 


:0>~K  N E , BOSTOM 


WtSCONSIN  SURVEY 


BULLETIN  57.  PLATE  20 


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205 


PLATE  20. 

Page 

Figs.  1-2.  Oloeocystopsis  Umneticus  (x  1000) 103 

Figs.  3-6.  Planktosphaeria  gelatinosa  (x  1000) 103 

Pigs.  7-10.  Asterococcus  Umneticus  (Fig.  7,  x 500;  figs.  8-10,  x 1000)  . 104 

Figs.  11-12.  DictyospJiaerium  Ehrenhergianum  (x  1000) 105 

Fig.  13.  Dictyosphaerium  pulcTiellum  (x  1000) 105 


206 


WISCONSIN  PHYTOPLANKTON 


PLATE  21. 

Page 

Fig.  1.  Dictyosphaerium  pulchellum  (x  1000) 105 

Figs.  2-3.  Westella  linearis  (x  1000) 107 

Fig.  4.  Westella  hotryoides  (x  1000) 107 

Fig.  5.  Dimorpiiococcus  lunatus  (x  1000) 106 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  21 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  22 


SMITH— ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  PHYTOPLANKTON 


207 


PLATE  22. 

Page 

Fig.  1.  Chlorella  vutff.aris  (x  1000) 108 

Fig.  2.  Trochiscia  reticularis  (x  1000) 109 

Fig.  3.  Oocystis  pusilla  (x  1000) Ill 

Fig.  4.  Oocystis  Borgei  (x  1000) Ill 

Fig.  5.  Oocystis  clliptica  (x  1000) Ill 

Fig.  6.  Oocystis  parva  (x  1000) 112 

Fig.  7.  Oocystis  gloeocystijormis  (x  1000) 112 

Figs.  8-9.  Oocystis  lacustris  (x  1000) 112 

Fig.  10.  Oocystis  sulymarina  (x  1000) 113 

Fig.  11.  Oocystis  solitaria  (x  1000) 113 

Figs.  12-13.  Oocystis  crassa  (x  1000) 113 


208 


WISCONSIN  PHYTOPLANKTON 


PLATE  23. 

Page 

Pigs.  1-2.  Oocystis  eremosphaeria  (x  1000) 113 

Fig.  3.  OoXyystis  panduriformis  var.  minor  (x  1000) 114 

Figs.  4-5.  Oocystis  natans  var.  major  (Fig.  4,  x 500;  fig.  5,  x 1000)..  114 

Figs.  6-7.  NepTirocytium  Agardhianum  (x  1000) 114 

Figs.  8-9.  Oloeotaenium  Loitleshergerianum  (x  400) 115 

Pigs.  10-13.  Tetraedron  muticum  var.  punctulatum  (x  1000) 116 

Figs.  14-16.  Tetraedron  trigonum  (x  1000) 116 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  23 


SMITH — ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  24 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  PHYTOPLANKTON  209 


PLATE  24. 

Page 

Figs.  1-4.  Tetraedron  trigonum  var.  setigerum  (x  1000) 117 

Figs.  5-9.  Tetraedron  trigonum  var.  gracile  (x  1000) 117 

Pigs.  10-13.  Tetraedron  yninimum  (x  1000) 118 

Fig.  14.  Tetraedron  regular e (x  1000) 118 

Figs.  15-16.  Tetraedron  regulare  var.  incus  (x  1000) L18 

Pigs.  17-18.  Tetraedron  regulare  var.  torsum  (x  1000) 119 

Figs.  19-22..  Tetraedron  victorieae  var.  major  (x  1000) 119 


14 


210 


WISCONSIN  PHYTOPLANKTON 


PLATE  25. 

Page 

Fig.  1.  Tetraedron  victorieae  var.  major  (x  1000) 119 

Figs.  ;2-3.  Tetraedron  verrucosum  (x  1000) 119 

Figs.  4-7.  TetraMron  caudatum  (x  1000) 120 

Figs.  8-12.  Tetraedron  eaudatum  var.  longispinum  (x  1000) 120 

Figs.  13-17.  Tetraedron  pentaMrieum  (x  1000) 120 

Fig.  1^.  TetraMron  hastatum  (x  1000) 121 

Figs.  19-21.  Tetraedron  hastatum  var.  palatinum  (x  1000) 121 

Figs.  22-24.  Tetraedron  constrictum  (x  1000) 122 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  25 


SMITH — ALGAE 


COCKAYNE 


BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  26 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  PHYTOPLANKTON  211 


PLATE  26. 

Page 

Figs.  1-5.  TetraMron  gracile  (x  1000) 122 

Figs.  6-7.  Tetraedron  lohulatum  (x  1000) 122 

Pig.  8.  Tetraedron  lolulatum  var.  polyfurcatum  (x  1000) 123 


212 


WISCONSIN  PHYTOPLANKTON 


PLATE  27. 

Page 

Figs.  1-3.  Tetraedron  limneticum  (x  1000) 123 

Figs.  4-5.  Tetraedron  planctonicum  (x  1000) 123 

Fig.  6.  Tetraedron  enorme  (x  1000) 124 

Figs.  7-8.  Polyedriopsis  spinulosa  (x  1000) 124 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  27 


SMITH — ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  28 


SMITH— ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  PHYTOPLANKTON 


213 


PLATE  28. 

Page 

Figs.  1-3.  Micractinium  pusillum  (x  1000) 125 

Fig.  4.  Micractinium  quadrisetum  (x  1000) 126 


214 


WI8G0N8IN  PHYTOPLANKTOIi^ 


PLATS  29. 

Page 


Fig.  1.  Micractinium  pusillum  var.  elegans  (x  1000) 126 

Figs.  2-3.  Golenkinia  radiata  (x  1000) 127 

Figs.  4-5.  Golenkinia  paucispina  (x  1000) 127 

Figs.  6-8.  Acanthosphaera  Zachariasi  (x  1000) 128 

Figs.  9-11.  E Chino spTiaerella  limnetica  (x  1000) 128 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  29 


SMITH — ALGAE 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  30 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  PHYTOPLANKTON 


215 


PLATE  30. 

Page 

Figs.  1-2.  Lagerheimia  citriformis  (x  1000) 130 

Figs.  3-4.  Lagerheimia  suhsala  (x  1000) 130 

Figs.  5-7.  Lagerheimia  Droescheri  (x  1000) 131 

Figs.  8-9.  Lagerheimia  longiseta  (x  1000) 130 

Figs.  10-12.  Lagerheimia  longiseta  var.  major  (x  1000) 130 


216 


WISCONSIN  PHYTOPLANKTON 


PLATE  31. 

Page 

Figs.  1-2.  Lagerheimia  ciliata  (x  1000) 129 

Fig.  3.  Lagerheimia  ciliata  var.  minor  (x  1000) 129 

Fig.  4.  Franceia  ovalis  (x  1000) 131 

Fig.  5.  Selenastrum  gracile  (x  1000) 133 

Figs.  6-7.  Selenastrum  Bihraianum  (x  1000) 133 

Figs.  8-10.  Selenastrum  Westii  (x  1000) 133 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  3! 


SMITH — ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  32 


COCKAYNE, BOSTON 


WISCONSIN  PHYTOPLANKTON 


217 


PLATE  32. 

Page 

Fig.  1.  Ankistrodesmus  falcatus  (x  1000) 134 

Fig.  2.  Ankistrodesmus  falcatus  var.  tumidus  (x  1000) 135 

Figs.  3-5.  Ankistrodesmus  falcatus  var.  miraMlis  (x  1000) 135 

Figs.  6-7.  Ankistrodesmus  spiralis  i(x  1000) 135 

Fig.  3.  Closteriopsis  longissima  var.  tropica  (x  400) 136 

Figs.  9-11.  Schroederia  Judayi  (x  1000) 137 

Fig.  12.  Schroederia  setigera  (x  1000) 137 


218 


WISCONSIN  PHYTOPLANKTON 


PLATE  33. 

Page 

Figs.  1-2.  Quadrigula  Pfitzeri  (x  1000) 138 

Fig.  3.  Quadrigula  Chodati  (x  1000) 138 

Figs.  4-6.  Quadrigula  lacustris  (Fig.  4,  x 500;  figs.  5-6,  x 1000) 139 

Fig.  7.  Elaktothrix  viridis  (x  825) 140 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  33 


SMITH— ALGAE 


COCKAYNE.  BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  34 


SMITH — ALGAE 


COCKAVNC. BOSTON 


WISCONSIN  PHYTOPLANKTON 


219 


PLATE  34. 

Page 

Figs.  1-3.  Elaktothrix  gelatinosa  (Figs.  1-2,  x 500;  fig.  3,  x 1000)  139 

Fig.  4.  Kirchneriella  lunaris  (x  1000) 141 

Fig.  5.  Kirchneriella  lunaris  var.  dianae  (x  100 141 


220 


WISCONSIN  PHYTOPLANKTON 


PLATE  35. 


Fig-  1.  Kirchneriella  lunaris  var.  irregularis  (x  1000) 

Figs.  2-3.  Kirchneriella  ohesa  (x  1000) 

Fig.  4.  Kirchneriella  ohesa  var.  major  (x  1000) 

Figs.  5-6.  Kirchneriella  ohesa  var.  aperta  (x  1000) 

Fig.  7.  Kirchneriella  contorta  (x  1000) 


Page 

142 

142 

142 

143 
143 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  35 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  36 


SMITH — ALGAE 


COCKAVNE.  BOSTOf^ 


WISCONSIN  PHYTOPLANKTON 


221 


PLATE  36. 

Page 

PMgs.  1-2.  Kirchneriella  elongata  (x  1000) 143 

Pig.  3.  Crucigenia  rectangularis  (x  1000) 144 

Figs.  4-5.  Crucigenia  irregularis  (x  1000) 145 

Fig.  6.  Crucigenia  crucifera  (x  1000) 145 

Figs.  7-9.  Crucigenia  truncata  (x  1000) 146 

Figs.  10-14.  Crucigenia  quadrata  (x  1000) 147 


222 


WISCONSIN  PHYTOPLANKTON 


PLATE  37. 

Page 

Fig.  1.  Crucigenia  apiculata  (x  1000) 146 

Fig.  2.  Crucigenia  tetrap'-ciia  (x  1000) 147 

Pig.  3.  Crucigenia  fenstrata  (x  1000) 148 

Fig.  4.  Crucigenia  Lauterhornei  (x  1000) 148 

Pigs.  5-6.  Tetrastrum  staurogeniaeforme  (x  1000) 149 

Figs.  7-11.  Tetradesmus  wisconsinensis  (x  1000) 150 

Figs.  12-14.  Scenedesmus  oMiquus  (x  1000) 151 

Figs.  15-17.  Scenedesmus  dimorphus  (x  1000) 151 

Figs.  18-20.  Scenedesmus  Hjuga  (x  1000) 152 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  37 


SMITH— ALGAE 


COCKAYNE.  BOSTOl 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  38 


SMITH — ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  PHYTOPLANKTON  223 


PLATE  38. 

Page 

Figs.  1-4.  Scenedesmus  acuminatus  (x  1000) 152 

Figs.  5-9.  Scenedesmus  Bernardii  (x  1000) 152 

Figs.  10-11.  Scenedesmus  Mjuga  var.  alternans  (x  1000) 153 

Figs.  12-14.  Scenedesmus  arcuatus  (x  1000) 153 

Figs.  15-16.  Scenedesmus  arcuatus  var.  capitatus  (x  1000) 153 


224 


WISCONSIN  PHYTOPLANKTON 


PLATE  39. 

Page 

Figs.  1-3.  Scenedesmus  arcuatus  var.  platydisca  (x  1000) 154 

Figs.  4-6.  Scenedesmus  acutiformis  (x  1000) 154 

Figs.  7-10.  Scenedesmus  armatus  (x  1000) 154 

Fig.  11.  Scenedesmus  armatus  var.  major  (x  1000) 155 

Figs.  12-14.  Scenedesmus  hrasiliensis  (x  1000) 155 

Figs.  15-16.  Scenedesmus  Tiystrix  (x  1000) 155 

Figs.  17-19.  Scenedesmus  denticulatus  (x  1000) 155 

Figs.  20-22.  Scenedesmus  longus  (x  1000) 156 

Figs.  23-25.  Scenedesmus  ahundans  (x  1000) 157 

Figs.  26-27.  Scenedesmus  ahundans  var.  longicauda  (x  1000) 157 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  39 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  40 


COCKAYNE,  OOSTOi 


-WISCONSIN  PHYTOPLANKTON 


225 


PLATE  40. 

Page 

Pigs.  1-2.  Scenedesmus  longus  var.  Naegelii  (x  1000) 156 

Figs.  3-5.  Scenedesmus  ahundans  var.  hrevicauda  (x  1000) 157 

Figs.  6-8.  Scenedesmus  ahundans  var.  asymmetrica  (x  1000) 157 

Figs.  9-11.  Scenedesmus  quadricauda  (x  1000) 158 

Figs.  12-14.  Scenedesmus  quadricauda  var.  longispina  (x  1000) 159 

Figs.  15-16.  Scenedesmus  quadricauda  var.  quadrispina  (x  1000) 158 

Fig.  17.  Scenedesmus  quadricauda  var.  parvus  (x  1000) 158 


15 


226 


WISCONSIN  PITYTOPLANKTON 


PLATE  41. 

Page 

Figs.  1-2.  Scenedesmus  quadricauda  var.  maximus  (x  1000) 159 

Figs.  3-7.  Scenedesmus  quadricauda  var.  Westii  (x  1000) 159 

Figs.  8-11.  Scenedesmus  opoliensis  (x  1000) 159 

Figs.  12-13.  Coelastrum  microporum  (x  825) 160 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  41 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57.  PLATE  42 


SMITH — ALGAE 


COCKAVNC, BOSTON 


WISCONSIN  PHYTOPLANKTON 


227 


PLATE  42. 

Page 

Fig.  1.  Coelastrum  microporum  (x  825) 160 

Figs.  2-3.  Coelastrum  camT)ricum  (x  825) 161 

Figs.  4-6.  Coelastrum  reticulatum  (x  825) 161 

Figs.  7-8.  Coelastrum  prohoscideum  (x  825) 162 


228 


WISCONSIN  PHYTOPLANKTON 


PLATE  43. 

Page 

Figs.  1-2.  Coelastrum  prohoscideum  (x  825).. 162 

Figs.  3-5.  Actinastrum  gracillimum  (x  1000) 164 

Figs.  6-7.  Actinastrum  HantzscM  (Fig.  6,  x 500;  fig.  7,  x 1000) 164 

Fig.  8.  Actinastrum  HantzscM  var.  elongatum  (x  1000) 165 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  43 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  44 


SMITH — ALGAE 


COCKAVNC.  BOSTOlM 


WISCONSIN  PHYTOPLANKTON 


229 


PLATE  44. 

Page 

Fig.  1.  Sorastrum  americanum  (x  1000) 163 

Figs.  2-3.  Sorastrum  americanum  var.  undulatum  (x  1000) 163 

PMgs.  4-5.  Sorastrum  spinulostim  (x  1000) 163 

Fig.  6.  Hydrodictyon  reticulatum  (x  100) 166 


{ 


r 


230 


WISCONSIN  PHYTOPLANKTON 


PLATE  45. 

Page 

Fig.  1.  Hydrodictyon  reticulatum  (x  266) 166 

Figs.  2-6.  Pediastrum  simplex  var.  duodenarium  (x  333) 167 

Pig.  7.  Pediastrum  integrum  (x  333) 168 

Figs.  8-10.  Pediastrum  integrum  var.  priva  (x  666) 168 

Fig.  11.  Pediastrum  araneosum  (x  333) 168 

Figs.  12-13.  Pediastrum  araneosum  var.  rugulosum  (Fig  12,  x 333, 

fig.  13,  X 666) 


168 


SMITH 


WISCONSIN  SURVEY 


BULLETIN 


57,  PLATE  45 


10 

ALGAE 


COCKAYNE, BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  46 


SMITH — ALGAE 


COCKAYNC, BOSTOi 


WISCONSIN  PHYTOPLANKTON 


231 


PLATE  46. 

Page 

Fig.  1.  Pediastrum  sculptatum  (x  333) 169 

Figs.  2-7.  Pediastrum  Boryanum  (x  333) 169 

Fig.  8.  Pediastrum  Boryanum  var.  undulatum  (x  333) 170 

Fig.  9.  Pediastrum  Boryanum  var.  longicorne  (x  333) 170 

Figs.  10-13.  Pediastrum  Eawraiskyi  (x  33S; 170 

Figs.  14-16.  Pediastrum  duplex  (x  333) 171 

Fig.  17.  Pediastrum  duplex  var.  roiundatum  (x  333) 172 


232 


WISCONSIN  PHYTOPLANKTON 


PLATE  47. 

Page 

Figs.  1-3.  Pediastrurti  duplex  var.  clathratum  (x  333) 171 

Figs.  4-7.  Pediastrum  duplex  var.  reticulatum  (x  333) 172 

Figs.  8-11.  Pediastrum  duplex  var.  gracillimum  (x  333) 172 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  47 


SMITH — ALGAE 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  48 


SMITH — ALGAE 


COCKAVNK 


BOSTOM 


WISCONSIN  PHYTOPLANKTON  233 


PLATE  48. 

Page 

Pigs.  1-2.  Pediastrum  duplex  var.  gracillimum  (x  333) 172 

Pigs.  3-4.  Pediastrum  duplex  var.  cohaerens  (x  333) 173 

Pigs.  5-8.  Pediastrum  biradiatum  (x  333) 173 

Pigs.  9-12.  Pediastrum  tetras  (x  666) 173 

Figs.  13-14.  Pediastrum  tetras  -var.  tetrabdon  (x  686) 174 


234 


WISCONSIN  PHYTOPLANKTON 


PLATE  49. 

Page 

Pigs.  1-2.  Pediastrum  tetras  var.  tetraodon  (x  1000).... 174 

Fig.  3.  Eaustropsis  RicJiteri  (x  1000) 175 

Figs.  4-7.  Characium  stipitatum  (x  1000) 176 

Figs.  8-15.  Characium  curvatum  (x  1000) 176 

Figs.  16-19.  Characium  cylindricum  (Fig.  16,  x 400;  figs.  17-19,  x 

1000)  177 

Figs.  20-24.  Characium  gracilipes  (x  1000) 178 

Figs.  25-29.  Characium  limneticum  (x  1000) 177 


COCKAYNE. BOSTON 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  50 


SMITH— ALGAE 


n 


COCKAVNC. BOSTON 


WISCONSIN  PHYTOPLANKTON  235 


PLATE  50. 

Page 

Figs.  1-3.  Cladophora  glomerata  (Figs.  1-2,  x 50,  fig.  3,  x 300) 182 

Figs.  4-5.  Ulothrix  suJ)constricta  (x  1000) 179 

Fig.  6.  Ulothrix  zonata  (x  400) 179 

Fig.  7.  Stigeoclonium  luhricum  (x  300) 180 

Fig.  8.  Aphanochaete  vermiculoides  (x  400) 181 


236 


WISCONSIN  PHYTOPLANKTON 


PLATE  51. 

Page 

Fig.  1.  Mougeotia  viridis  (x  400) 184 

Fig.  2.  Zygnema  pectinatum  (x  400) 185 

Fig.  3.  Spirogyra  porticaUs  (x  400) 185 


WISCONSIN  SURVEY 


BULLETIN  57,  PLATE  5 


SMITH — ALGAE 


COCKAYNE. BOSTON 


\ 


OF  THE 

UNIVERSITY  OF  (LIINOIS 


I 


INDEX 


Page 


Acanthococcus  reticularis  Reinsch. ..  109 

ACANTHOSPHAERA  Lemm 128 

A.  ZACHARIASI  Lemm.  pi.  29,  f.  6-8.  . 128 

ACTINASTRUM  Lag 164 

A.  GRACILLIMUM  G.  M.  Smith  pi. 

^3,  f.  S-5 164 

A.  HANTZSCHI  Lag.  pi.  ^5,  f.  6-7 164 

V.  ELONGATUM  G.  M.  Smith  pi.  J,3, 

f.  8 165 

AKONTAE 183 

ANABAENA  Bory 55 

A.  AFFINIS  Lemm.  pi.  8,  f.  7 57 

A.  AUGSTUMALIS  v.  MARCHICA 

Lemm.  pi.  8,  f.  9-10 58 

A.  BORNETIANA  Collins  pi.  8,  f.  S.  . 58 

A.  CIRCINALIS  (Ktz.)  Rab.  pi.  9, 

f.  i-5 59 

V.  MACROSPORA  (Wittr.)  de  Toni 

pi.  9,  f.  6;  pi.  JO,  f.  jf 60 

A.  FLOS- AQUAE  (Lyng.)  Breb.  pi.  10, 

f.  2-4 60 

A.  fios-aquae  Klebh.  non  (Lyng.) 

Breb 61 

V.  TRELEASII  Born.  & Flah.  pi.  10, 

f.  5-7 60 

A.  Hassallii  (Ktz.)  Wittr 59 

V.  macrospora  Wittr 60 

A.  LEMMERMANNI  P.  Richt.  pi.  10, 

f.  8;  pi.  JJ,  f.  J Cl 

A.  LEVANDERI  Lemm.  pi.  8,  f.  4-5.  . 58 

A.  LIMNETIC  A G.  M.  Smith  pi.  8,  f.  8 57 

A.  MACROSPORA  v.  ROBUSTA 

Lemm.  pi.  8,  f.  6 57 

A.  mendotae  Trelease 60 

A.  PLANCTONICA  Brunnth.  pi.  8,  t.  2 56 

A.  SPIROIDES  V.  CRASSA  Lemm. 

pi.  9,  f.  1-S 59 

Anacystis  pulverus  Wood 40 

ANKISTRODESMUS  Corda  134 

A.  Chodati  (Tanner-Fullman) 

Brunnth 138 

A.  FALCATUS  (Corda)  Ralfs 

pi.  32,  f.  J 134 

V.  ACICULARIS  (A.  Br.) 

G.  S.  West  135 

V.  MIRABILIS  (W  & G.  S.  West) 

G.  S.  West  pi.  32,  f.  3 — 5 135 

V.  spiralis  (Turn.)  G.  S.  West.  . . 135 
V.  TUMIDUS  (W.  & G.  S.  West) 

G.  S.  West  pi.  32,  f.  2 135 


Page 

A.  lacustre  (Chodat)  Ostenfeld  139 

A.  longissimum  v.  septatum 

(Chodat)  Brunnth 177 

A.  Pfitzeri  (Schrod.)  G.  S.  West 138 

A.  SPIRALIS  (Turn.)  Lemm. 

pi.  32,  f.  6—7 135 

APHANIZOMENON  Morren  61 

A.  FLOS-AQUAE  (L.)  Ralfs 

pi.  11,  f.  2—4 61 

APHANOCHAETACEAE 181 

APHANOCHAETE  A.  Br 181 

A.  VERMICULOIDES  Wolle 

pi.  50,  f.  8 181 

APHANOCAPSA  Nag 41 

A.  DELICATISSIMA  W.  &.  G.  S. 

West  pi.  2,  f.  7 41 

A.  ELACHISTA  v.  CONFERTA 

W.  & G.  S.  West  pi.  2,  f.  8 42 

V.  PLANCTONICA  G.  M. 

Smith  pi.  3,  f.  3 42 

A.  ENDOPHYTICA  G.  M.  Smith 

pi.  2,  f.  JO 42 

A.  GREVILLEI  (Haas.)  Rab. 

pi.  3,  f.  J 43 

A.  PULCHRA  (Ktz.)  Rab.  pi.  2,  f.  9.  42 

A.  RIVULARIS  (Carm.)  Rab. 

pi’.  3,  f.  2 43 

APHANOTHECE  Nag 43 

A.  CLATHRATA  W.  & G.  S.  West 

pi.  6,  f.  3 44 

A.  NIDULANS  P.  Richt.  pi.  6,  f.  J 44 


V.  ENDOPHYTICA  W.  & G.  S. 

West  pi.  5,  f.  6 44 

A.  PR  A SIN  A A.  Br.  pi.  5,  f.  5 45 

A.  STAGNINA  (Spreng.)  A.  Br. 


pi.  6,  £.  2 45 

ASTEROCOCCUS  Scherffel  103 

A.  LIMNETICUS  G.  M.  Smith 

pi.  20,  f.  7— JO 104 

Autocolony  109 

AUTOSFORACEAE 109 

Autospore  109 

BOTRYOCOCCACEAE  83 

BOTRYOCOCCUS  Ktz 83 

B.  BRAUNII  Ktz.  pi.  J5,  f.  5 84 

B.  Braunii  G.  S.  West  non  Ktz 83 

B.  PROTUBERANS  v.  MINOR 

G.  M.  Smith  pi.  15,  f.  6—7 85 


B.  SUDETICUS  Lemm.  pi.  15,  t.  8 83 

CARTERIA  Diesing 92 


238 


INDEX 


Page 

C.  CORDIFORMIS  (Carter)  Diesing 


pi,  16,  f.  1 92 

C.  KLEBSII  (Dang.)  Dill 

pi.  16,  f.  2 — If 93 

CARTERIACBAE  92 

CHAETOPHORACEAE  180 

CHARACIUM  A.  Br 175 

C.  CURVATUM  G.  M.  Smith 

pi.  Jfi,  f.  8 — 15 176 

C.  CYLINDRICUM  Lamb. 

pi.  ^9,  f.  16—19 177 

C.  GRACIDIPES  Lamb.  pi.  J,9,  f.  20—24  178 
C.  LIMNETICUM  Lemm. 

pi.  49,  f.  25 — 29 177 

C.  STIPITATUM  (Bachman)  Wille 

pi.  49,  f.  4—7 176 

CHLAMYDOMONADACEAE  90 

CHLAMYDOMONAS  Ehr 90 

C.  communis  Snow  91 

C.  DINOBRYONI  G.  M.  Smith 

pi.  16,  f.  5—7 91 

C.  EPIPHYTICA  G.  M.  Smith 

pi.  16,  f.  11— IS 91 

C.  GLOBOSA  Snow  pi.  16,  f.  8 90 

C.  SNOWII  Printz  pi.  16,  f.  9 — 10.  ...  91 

CHLORAMOEBACEAE  79 

CHLORELLA  Beyerinck  108 

C.  VULGARIS  Beyerinck  pi.  22,  f.  1..  . 108 

CHLOROBOTRYDACEAE  82 

CHLOROBOTRYS  Bohlin  82 

C.  LIMNETICUS  G.  M.  Smith 


Page 


C.  MINUTUS  (Ktz.)  Nag.  pi.  1,  f.  1.  . . 28 

C.  TURGIDUS  (Ktz.)  Nag.  pi.  1,  f.  9.  3i 

CHRYS AMOEBA  Klebs  67 

C.  RADIANS  Klebs  pi.  12,  f.  1 67 

CHRYSIDASTRUM  Lauterborn 78 

C.  CATENTATUM  Lauterborn 

pi.  14,  f.  7—8 78 

CHRYSOMONADINEAE  65 

CHRYSOSPHAERELLA  Lauterborn  69 

C,  LONGISPINA  Lauterborn 

pi.  12,  f.  7—8 69 

CLADOPHORA  Ktz 182 

C.  GLOMERATA  (L.)  Ktz. 

pi.  50,  f.  1 — S 182 

CLADOPHORACEAE 182 

Clathrocystis  aeruginosa  (Ktz.) 

Henfrey 39 

CLOSTERIOPSIS  Lemm 136 

C.  LONGISSIMA  v.  TROPICA  W. 

& G.  S.  West  pi  32,  f.  8 136 

COCCOGONEALES  26 

COCCOMYXA  Schmidle  139 

COELASTREAE I6O 

COELASTRUM  Nag ] 160 

C.  CAMBRICUM  Arch,  pi,  42,  f.  2 — 3.  161 

C.  compositum  G.  S.  West  162 

C.  MICROPORUM  Nag.  pi.  41,  f. 

12— IS;  pi.  42,  t.  1 160 

C.  PROBOSCIDEUM  Bohlin  pi.  42,  f. 

7—8;  pi.  43,  f.  1—2 162 

C.  RETICULATUM  (Dang.)  Senn 


pi.  15,  f.  9 82 

C.  REGULARIS  (W.  West)  Bohlin 

pi.  15,  f.  16 82 

CHLOROCHROMONAS  Lewis 80 

C.  MINUTA  Lewis  pi.  15,  f.  1—S 80 

Chlorococcus  regulare  W West 82 

CHLOROPHYCEAE 88 

CHLOROSACCACEAE  81 

Chodatella  ciliata  (Lag.)  Lemm 129 

V.  minor  G.  M,  Smith 129 

C.  citriformis  Snow 130 

C.  DroescTieri  Lemm 131 

C.  longiseta  Lemm 130 

G.  subsala  Lemm 130 

CHROMULINALES 66 

CHROOCOCCACEAE  27 

CHROOCOCCUS  Nag 27 

C.  DISPERSUS  (V.  Keiss.)  Lemm. 

pi.  1,  f.  2 28 

V.  MINOR  G.  M.  Smith  pi.  1,  f.  3.  28 

C.  GIGANTEUS  W.  West,  pi.  2,  f.  1. ..  30 

C.  LIMNETICUS  Lemm.  pi.  1,  t.  4-  ...  29 

V.  CARNEUS  (Chod.)  Lemm. 

pi.  1,  f.  6 30 

V.  DI STANS  G.  M.  Smith 

pi.  1,  f.  7 30 

V.  ELEGANS  G.  M.  Smith 

pi.  1,  f.  8 30 

V.  SUBSALSUS  Lemm.  pi.  1,  f.  5.  29 

Chroococcus  minor  var  dispersus 

V.  Keiss 28 


pl.  42,  f.  4—6 161 

COELOSPHAERIUM  Nag 33 

C.  DUBIUM  Grunow  pl,  3,  f.  7 35 

C.  KUETZINGIANUM  Nag, 

pl.  3,  f.  4—5 34 

C.  NAEGELIANUM  Unger 

pl.  3,  f.  6;  pl.  .J,  f.  1 35 

Coenocyte  88 

Cohniella  staurogeniae forme  SchrOder  149 

Collection  methods 10 

Conferva  echinulata  J.  E.  Smith 63 

CONJUGALES  183 

CRUCIGENIA  Morren 144 

C.  APICULATA  (Lemm.)  Schmidle 

pl.  37,  f.  1 146 

C.CIRUCIFERA  (Wolle)  Collins 

pl.  36,  f.  6 145 

C.  FENESTRATA  Schmidle  pl.  37,  f.  3.  148 
C.  IRREGULARIS  Wille  pl.  36,  f.  f— 5.  145 
C.  LAUTERBORNEI  Schmidle 

pl.  .37,  f.  .J 148 

C.  QUADRATA  Morren  pl.  36,  f.  10— 14.  147 

V.  punctata  (Schmidle)  147 

C.  RECTANGULARIS  (Nag.)  Gay 

pl.  .36,  f.  3 144 

C.  TETRAPEDIA  (Kirchner)  W & G. 

S.  West  pl.  37,  f.  2 147 

G.  triangularis  (Chodat)  Schmidle....  147 
C.  TRUNCATA  G.  M]  Smith 

pl.  36,  f.  7—9 146 

CRUCIGENIEAE  14-3 


INDEX 


239 


Pag-e  1 


DACTYLOCOCCOPSIS  Hansg 47 

D.  ACICULARIS  Lemm.  pi.  6,  f.  8—10  48 

D.  RHAPHIDIOIDES  Hansg. 

pi.  6,  f.  7 47 

DICTTOSPHAERIACEAE  104 

DICTYOSPHAERIUM  Nag 104 

D.  EHRENBERGIANUM  Nag. 

pi.  20,  f.  11—12 105 

D.  PULCHELLUM  Wood  pi.  20, 

f.  13;  pi.  21,  f.  1 105 

DIMORPHOCOCCUS  A.  Br 108 

D.  LUNATUS  A.  Br.  pi.  21,  t.  5 106 

DINOBRYON  Ehr 72 

D.  BAVARICUM  Imhof  pi.  13,  t.  10.  . . 73 

D.  CALICIFORME  Bachm. 


Page 


GLOEOTRICHIA  J.  G.  Ag 63 

I G.  ECHINULATA  (J.  E.  Smith)  P. 

i Richt.  pi.  11,  f.  5 — 6 63 

! G.  visum  Born,  et  Flah.  non  Thur.  ...  63 

iGOLENKINIA  Chodat  127 

I G.  PAUCI SPINA  W.  & G.  S.  West 

pi.  29,  f.  Jf—5 127 

G.  RADI  AT  A Chodat  pi.  29,  f.  2—3.  . . 127 

GOMPHOSPHAERIA  Ktz 36 

G.  AFONINA  Ktz.  pi.  k,  t 2—3 37 

V.  CORDIFORMIS  Wolle  pi.  !,,  t.  It  37 

G.  LACUSTRIS  Chodat  pi.  4.  f.  5 36 

G.  Naegeliana  (Unger)  Lemm 35 

i GONIUM  Mueller 94 

I G.  PECTORALE  Mueller 


pi.  13,  f.  5—6 73 

D.  DIVERGENS  Imhof  pi.  1^,  f.  2 75 

D.  SETULARIA  Ehr.  pi.  13,  f.  13; 

V\.  lit,  i.  1 74 

D.  SOCIALE  Ehr.  pi.  13,  f.  12 74 

D.  STIPITATUM  Stein  pi.  13,  f.  11.  .. . 74 

D.  TABELLARIAE  (Lemm.)  Pascher 

pi.  13,  f.  7 — 9 73 

D.  utriculus  var.  tabellariae  Lemm.  ..  73 

DINOBRYONACEAE  72 

ECHINOSPHAERELLA  G.  M.  Smith  128 

E.  LIMNETICA  G.  M.  Smith 

pi.  29,  f.  9—11 128 

ECHINOSPHAERIDIUM  Lemm 128 

ELAKTOTHRIX  Wille 139 

E.  GELATINOSA  Wille  pi.  3!,,  t.  1—3  139 
E.VIRDIS  (Snow)  Printz  pi.  S3,  f.  7.  140 

EUASTROPSIS  Lag 174 

E.  RICHTERI  (Schmidle)  Lag. 

T>1.  If9,  t.  3 175 

Euastrum  tetraodon  Corda 174 

EUCHROMULINACEAE  66 

EUCHRYSOMONADINAE  66 

EUDORINA  Ehr 95 

E.  ELEGANS  Ehr.  pi.  19,  /.  1 96 

EUHYMENOMONADACEAE  70 

Euplankton  1 

Facultative  plankton 1 

FRANCEIA  Lemm 131 

F.  OVALIS  (Franck)  Lemm.  pi.  31,  f.  /,  131 

Fusola  virdis  Snow  140 


pi.  16,  f.  U — 15 

Heleoplankton  

Ilerposteiron  hyalothecae  Hansg 

HETEROCHLORIDALES  

IlETEROCOCCALES  

Hormogones  

I-IETEROKONTAE  

PIETEROTRICHALES  

HORMOGONEALES  

Hormogones  

HYALOBRYON  Lauterborn  

H.  Lauterhornei  var  mucicola  Lemm. 
H.  MUCICOLA  (Lemm.)  Pascher 

pi.  Ilf,  f.  3 — ^ 

KYDRODICTYACEAE  

HYDRODICTYON  Roth 

H.  RETICULATUM  (L.)  Lag. 

pi.  f.  6;  Pl.  45,  f.  1 

HYDRURINEAE  

Ineffigiata  neglecta  W.  & G.  S.  West 

ISOCHRYSIDALES  

ISOKONTAE  

Key  to  the  genera  

KIRCHNERIELLA  Schmidle  

K.  aperta  Teiling 

K.  CONTORTA  (Schmidle)  Bohlin 

pi.  35,  f.  7 

K.  ELONGATA  G.  M.  Smith 

pi.  36,  f.  1 — 2 

K.  LUNARIS  (Kirchner)  Mobius 

pi.  3//,  f.  4 


94 

5 

181 

79 

80 
26 
79 
86 
48 
48 
75 
75 

75 
165 

165 

166 

76 
84 


21 

140 
143 

143 

143 

141 


Gas  vacuoles  33 

Geography  of  Wisconsin 5 

Geology  of  Wisconsin  5 

GLOEOCOCCUS  102 

GLOEOCYSTIS  Nag 100 

G.  GIGAS  (Ktz.)  Lag.  pi.  19,  f.  2 101 

GLOEOCYSTOPSIS  G.  M.  Smith 102 

G.  LIMNETICUS  G.  M.  Smith 

pi.  20,  f.  1—2 103 

GLOEOTHECE  Nag 45 

G.  LINEARIS  Nag.  pi.  6,  f.  5 46 

V.  COMPOSITA  G.  M.  Smith 


V.  DIANAE  Bohlin  pi.  34,  f.  5.  ...  141 
V.  IRREGULARIS  G.  M.  Smith 

pi.  35,  f.  i 142 

K.  OBESA  (W.  West)  Schmidle 

pi.  35,  f.  2—3 142 

V.  APERTA  (Teiling)  Brunnthaler 

pi.  35,  f.  5—6 143 

V.  contorta  Schmidle 143 

V.  MAJOR  (Bernard)  G.  M. 

Smith  pi.  35,  f.  4 142 

LAGERHEIMIA  Chodat  129 


L.  CILIATA  (Lag.)  Chodat 


pi.  6,  f.  6 46 

GLOEOTAENIUM  Hansg 115 

G.  LOITLESBERGERIANUM  Hansg. 

pi.  23,  f.  8 — 9 115 


pi.  31,  f.  1 — 2 129 

V.  MINOR  G.  M.  Smith  pi.  31,  f.  3.  129 
L.  CITRIFORMIS  (Snow)  G.  M. 

Smith  pi.  30,  f.  1—2 130 


240 


INDEX 


Page 


L.  DROESCHERI  (Lemm.)  Printz 

pi.  30,  f.  5 — 7 131 

L.  LONGISETA  (Lemm.)  Printz 

pi.  30,  f.  8—9 130 

V.  MAJOR  G.  M.  Smith 

pi.  30,  f.  10 — 12 130 

L.  SUBSALSA  Lemm.  pi.  30,  f.  3—1  . . 130 

Lake  areas  of  Wisconsin 6 

Lakes 

Altitude 6 

Chemical  composition  of  water  . . 8 

Formation  of  Wisconsin  Lakes  . . 5 

Hard  water  7 

Medium  water 7 

Origin  of  Names 11 

Size  5 

Soft  water  7 

Temperature  6 

Lemmermannia  emarginata 


Pago 


M.  octonarius  Bailey  167 

MOUGEOTIA  C.  A.  Ag 184 

M.  VIRIDIS  (Ktz.)  Wittr.  pi.  51,  f.  1.  184 
Myxonema  lubricum  (Dillw.)  Fries...  180 

MYXOPHTCEAE 26 

OCHROMONADACEAE  71 

OCHROMONADALES 70 

OOCTSTEAE 110 

Oocystella  Lemm 114 

OOCYSTIS  Nag 110 

O.  BORGEI  Snow  pi.  22,  f.  Ill 

O.  ciliata  Lag 129 

O.  CRASS  A Wittr.  pi.  22,  f.  12—13 113 

O.  ELLIPTICA  W.  West  pi.  22,  f.  5.  . . Ill 
O.  EREMOSPHAERIA  G.  M.  Smith 

pi.  23,  f.  1-2 113 

O.  GLOEOCYSTIFORMIS  Borge  pi.  22, 

f.  7 112 

O.  LACUSTRIS  Chodat  pi.  22,  f.  8—9.  112 


(Schroder)  Chodat 147 

Lemmermannia  tetrapedia  (Kirch- 

ner)  Lemm 148 

List  of  Lakes  studied  13-19 

LYNGBYA  C.  A.  Ag 52 


L.  BIRGEI  G.  M.  Smith  pi.  7,  f.  U — 15.  54 

L.  CONTORT  A Lemm.  pi.  7,  f.  12—13.  53 

L.  LIMNETIC  A Lemm.  pi.  7,  f.  9—11.  52 


L.  Wollei  Farlow  54 

L.  Wollei  Trelease  non  Farlow 54 

MALLOMONADACEAE  67 

MALLOMONAS  Perty  67 


M.  ALPINA  Pascher  & Ruttner 


O.  NATANS  V.  MAJOR  G.  M.  Smith 

pi.  23,  f.  4-5 114 

O.  PANDURIFORMIS  v.  MINOR  G. 

M.  Smith  pi.  23,  f.  .3 114 

O.  PARVA  W.  & G.  S.  West  pi.  22,  f.  6 112 

O.  PUSILLA  Hansg.  pi.  22,  i.  3 Ill 

O.  SOLITARIA  AVittr.  pi.  22,  f.  11 113 

O.  SUBMARINA  Lag.  pi.  22,  f.  10 113 

OPHIOCYTIACEAE 85 

OPHIOCYTIUM  Nag 85  ^ 

O.  CAPITATUM  Wolle  pi.  15,  f.  12-13.  86 

V.  LONGISPINUM  (Mobius)  Lemm. 
pi.  15,  f.  U-16 86 


pi.  12,  f.  4 

M.  CAUDATA  Iwanoff  pi.  12,  f.  6.  . . . 
M.  PRODUCTA  (Zach.)  Iwanoff 


68  O.  PARVULUM  (Perty)  A.  Br.  pi.  15, 

69  t.  11 86 

OSCILLATORIA  Vaucher  50 


pi.  12,  f.  2 68 

V.  MARCHICA  Lemm.  pi.  12,  f.  3.  68 

M.  TONSURATA  Telling  pi.  12,  f.  5.  . . 68 

MERISMOFEDIA  Meyen 31 

M.  ELEGANS  A.  Br.  pi.  2,  f.  5 32 

V.  MAJOR  G.  M.  Smith  pi.  2,  f.  6.  32 

M.  GLAUCA  (Ehr.)  Niig.  pi.  2,  f.  4 ‘12 

M.  PUNCTATA  Meyen  pi.  2,  f.  3 33 

M.  TENUISSIMA  Lemm.  pi.  2,  f.  2.  . . 33 

MICRACTINIEAE  125 

MICRACTINIUM  Fresenius  125 

M.  PUSILLUM  Fresenius 

pi.  28,  f.  1—3 125 

V.  ELEGANS  G.  M.  Smith 

pi.  29,  f.  1 126 

M.  QUADRISETUM  (Lemm.)  G.  M. 

Smith  pi.  28,  f.  4 126 

MICROCYSTIS  Ktz 38 

M.  AERUGINOSA  Ktz.  pi.  5,  f.  2—3.  39 

V.  MA.lOR  (Wittr.)  G.  M.  Smith 

pi.  4,  f.  6 40 

M.  FLOS-AQUAE  (Wittr.)  Kirchner 

pi.  .5,  f.  1 39 

M.  ICHTHYOBLABE  Ktz 38 

M.  INCERTA  Lemm.  pi.  5,  f.  4 40 

M.  PULVERA  (Wood)  Migula 40 

Monaciinus  duodcnarius  Bailey 167 


O.  PROLIFICA  (Grev.)  Gom.  pi.  7, 


f.  3-5 51 

O.  RUBESCENS  D.  C 51 

O.  TENUIS  C.  A.  Ag.  pi.  7,  f.  6 52 

V.  TERGESTINA  (Ktz.)  Rab.  pi.  7, 

f.  7-8 52 

OSCILLATORIACEAE  49 

PALMELLACEAE 100 

PANDORINA  Bory  95 

P.  MORUM  Bory  pi.  16,  f.  16-17 95 

PEDIASTRUM  Meyen 166 

P.  ARANEOSUM  Racib.  pi.  45,  f.  11..  168 

V.  RUGULOSUM  (G.  S.  West)  G.  M. 

Smith  pi.  45,  f.  12-13 168 

P.  BIRADIATUM  Meyen  pi.  48,  f.  5-8  173 

P.  BORYANUM  (Turp.)  Menegh.  pi. 

46,  f.  2-7 169 

V.  LONGICORNE  Racib.  pi.  46,  f.  9.  170 
y.  longicorne  forma  glabrum  Racib.  170 
V.  longicorne  forma  granulatum 

Racib 170 

V.  UNDULATUM  Wille  pi.  46,  f.  8.  . 170 

P.  DUPLEX  Meyen  pi.  46,  f.  U-16 171 

V.  CLATHRATUM  (A.  Br.)  Lag. 

pi.  47,  f.  1-3 171 

V.  COHAERENS  Bohlin  pi.  48,  f.  3-4  173 


INDEX 


241 


V.  GRACILLIMUM  W.  & G.  S.  West 

pi.  JfT,  f.  8-11;  pi.  172 

V.  RETICULATUM  Lag.  pi.  ^7,  f . 4-7  172 
V.  reticulatum  forma  cohaerens 

(Bohl.)  Brunnth 173 

V.  ROTUND ATUM  Lucks  pi.  1,6,  t.  17  172 

P.  INTEGRUM  Nag.  pi.  45,  f.  7 168 

V.  PRIVA  Printz  pi.  45,  f.  8-10 168 

P.rotula  (Ehr.)  A.  Br 173 

P.  SCULPTATUM  G.  M.  Smith  pi.  46, 

t.  1 169 

P.  SIMPLEX  V.  DUODENARIUM 

(Bailey)  Rab.  pi.  45,  f.  2-6 167 

V.  clathratum  (Schroter)  G.  S.  West  167 
P.  TETRAS  (Ehr.)  Ralfs  pi.  48,  f.  9-12  173 

V.  OBTUSATA  Racib 174 

V.  TETRAODON  (Corda)  Hansg. 


Page 


Relative  abundance  of  different  species  28 

RHABDODERMA  Schmidle  & Lauter- 

born  46 

R.  LINEARE  Schmidle  & Lauterborn 

pl.  6,  f.  4 47 

Bhaphidium  Braunii  var.  lacustre 

Chodat 139 

R.  Chodati  Tanner-Fullman 138 

R.  longissimum  var.  septatum  Chodat  177 

V.  tropicum  W.  & G.  S.  West 136 

B.  Pfitsieri  SchrOder 138 

B.  spirale  Turner 135 

RHIZOCHRYSIDINAE 77 

RHIZOCHRTSIS  Pascher  77 

R.  LIMNETIC  A G.  M.  Smith  pl.  14,  t.  6 77 

R.  PLANCTONICA  Pascher 78 

Bichteriella  botryoides  (Schmidle) 


pl.  48,  f.  IS-IJ, ; pl.  1,9,  t,  1-2 174  Lemm 

PERONIELLA  Gobi  81  I forma  fenestrata  Chodat 

P.  PLANCTONICA  G.  M.  Smith  pl.  > forma  tetraedrica  Lemm. 


15.  f.  4 81 

PHAEOCAPSACEAE  76  ' 

PHAEOCAPSALES  76 

PHAEOCOCCUS  Borzi  76  ' 

P.  PLANCTONICUS  W.  & G.  S.  West  1 

pl,  14,  f.  5 76  : 

PHAEOPHYCEAE  65 

Phythelois  ovalis  France  131 

Phytoplankton  1 

Pithiscus  Klebsii  Dangeard 93 

PLANKTOSPHAERIA  G.  M.  Smith..  103 
P.  GELATINOSA  G.  M.  Smith  pl.  20, 

f.  3-6 103 

PLANOSPORACEAE  175 

PLECTONEMA  WOLLEI  Farlow 54  ' 

PLEODORINA  Shaw  96  ’ 

P.  CALIFORNICA  Shaw  pl.  17,  f.  1-S  97 

Polycystis  ichthyohlabe  Ktz 88 

POLYEDRIOPSIS  Schmidle  124 

P.  SPINULOSA  Schmidle  pl.  27,  f.  7-8  124 

Polyedrium  gracile  Reinsch 122 

P.  hastatum  var.  palatinum  Schmidle  121 
P.  lobulatum  Nag 122 


Bivularia  echinulata  J.  E.  Smith 

RIVULARIACEAE  

SCENEDESMUS  Meyen  

S.  ABUNDANS  (Kirchner)  Chodat  pl. 

SO,  f.  23-26 

V.  ASYMMETRICA  (Schrdder)  G. 

M.  Smith  pl.  46,  f.  6-8 

V.  BREVICAUDA  G.  M.  Smith  pl. 

46,  f.  3-5 

V.  LONGICAUDA  G.  M.  Smith  pl. 

39,  f.  26-27 

S.  ACUMINATES  (Lag.)  Chodat  pl. 

58,  f.  i-4 

S.  ACUTIFORMIS  SchrOder  pl.  39,  f. 

4-6  

S.  alternans  Reinsch 

S.  ARCUATUS  Lemm.  pl.  58,  f.  12-11,.  . 
V.  CAPITATUS  G.  M.  Smith  pl.  38, 

f.  15-16 

V.  PLATYDISCA  G.  M.  Smith  pl.  39, 

f . 1 — 3 

S.  ARMATUS  (Chodat)  G.  M.  Smith 
pl.  39,  f . 7-10 


P.  muticum  v.  punctulatum  Reinsch..  116 

P.  tetraedricum  Nag 118 

V.  hastatum  Reinsch 121 

P,  trigonum  Nag 117 

V.  gracile  Reinsch 117 

V.  setigerum  (Arch.)  SchrOder 117 

PROTOCOCCACEAE  108  i 

PROTOCOCCALES  99 

Protococcus  mmutus  Ktz 28 

Pseudocilia 102 

Pseudovacuoles  33 

Pyrenoids  88 

QUADRIGULA  Printz  137 

Q.  CHODATI  (Tanner-Fullman)  G. 

M.  Smith  pl.  35,  f.  3 138 

Q.  LACUSTRIS  (Chodat)  G.  M. 

Smith  pl.  33,  f.  4-6 139 


v.MAJOR  G.  M.  Smith  pl.  39,  f.  11.. 
S.  BERNARDII  G.  M.  Smith  pl.  38,  f. 

5-9 

S.  BIJUGA  (Turpin)  Lag.  pl.  37,  f. 

18-20  

V.  ALTERNANS  (Reinsch)  Borge 

pl.  38,  f.  10-11 

S.  bijugatus  (Turpin)  Ktz 

S.  BRASILIENSIS  Bohlin  pl.  39,  f. 

12-14  

B.  caudatus  Nag.  non  Corda 

S.  DENTICULATUS  Lag.  pl.  39,  f. 

17-19  

S.  DIMORPHUS  (Turpin)  Ktz.  pl.  37, 

f.  15-17 

S.  HYSTRIX  Lag.  pl.  39,  f.  15-16 

S.  LONGUS  Meyen  pl.  39,  f.  20-22 


125 

125 

126 
6S 
62 

150 

157 

157 

157 

157 

152 

154 

153 
153 

153 

154 

154 

155 

152 

152 

153 
152 

155 

156 

155 

151 

155 

156 


Q.  PFITZERI  (Schrdder)  G.  M.  v.  NAEGELII  (Breb.)  G.  M.  Smith 

Smith  pl.  S3,  f.  1-2 138  ; pl.  46,  f.  1-2 156 


242 


INDEX 


Page ! 


S.  Naegeln  Breb 156 

S.  OBLIQUUS  (Turpin)  Ktz.  pi.  37, 

f.  72-74 151 

S.  OPOLIENSIS  P.  Kichter  pi.  41,  f. 

8-77 159 

S.  QUADRICAUDA  (Turpin)  Breb. 

pi.  JfO,  f.  9-11 158 

V.  ahundans  (Kirchner)  Lag 157 

V.  asymmetrica  SchrOder  157 

V.  LONGISPINA  (Chodat)  G.  M. 

Smith  pi.  JfO,  f.  IS-U 159 

V.  MAXIMUS  W.  & G.  S.  West  pi. 

47.  f.  1-2 159 

V.  PARVUS  G.  M.  Smith  pi.  J,0,  f.  17  158 
V.  QUADRISPINA  (Chodat)  G.  M. 

Smith  pi.  40.  f.  15-16 158 

V.  setosus  ( Kirchner  ■>  Lag 156 

V.  WESTII  G.  M.  Smith  pi.  47,  f. 

5-7  159 

SCHROEDERIA  Lemm 136 

S.  JUDATI  G.  M.  Smith  pi.  52,  f.  9-11  137 
S.  SETIGERA  (SchrOder)  Lemm.  pi. 

52,  f.  72 137 

SELENASTREAE  132 

SELENASTRUM  Relnsch  132 

S.  acuminatum  G.  S.  West  non  Lag.  133 

8.  acuminatum  Lag 152 

S.  BIBRAIANUM  Reinsch 


Page 


TETRADESMUS  G.  M.  Smith 150 

T.  WISCONSINENSIS  G.  M.  Smith 

pi.  57,  f.  7—11 150 

TETRAEDREAE  I15 

TETRAEDRON  Ktz II5 

T.  arthrodesmiforme  v.  lohulatum 

Wolosz 122 

T.  CAUDATUM  (Corda)  Hansg. 

pi.  25,  f.  4 — 7 120 

V.  LONGISPINUM  Lemm.  pi.  25, 

f.  8-12 120 

T.  CONSTRICTUM  G.  M.  Smith 

pi.  25,  f.  22—24 122 

T.  ENORME  (Ralfs)  Hansg.  pi.  27,  t.  6.  124 
T.  GRACILE  (Reinsch)  Hansg. 

pi.  25,  f.  7 — 5 122 

T.  HASTATUM  (Reinsch)  Hansg. 

pi.  25,  f.  78 121 

V.  PALATINUM  (Schmidle) 

Lemm.  pi.  25,  f.  19—21 121 

T.  LIMNETICUM  Borge  pi  27,  f.  7—5.  123 
T.  LOBULATUM  (Nag.)  Hansg. 

pi.  26,  f.  6—7 122 

V.  POLTFURCATUM  G.  M. 

Smith  pi.  26,  £.  8 123 

T.  MINIMUM  (A.  Br.)  Hansg. 

pi.  24,  f.  10— IS 118 

T.  MUTICUM  V.  FUNCTULATUM 


pi.  57,  f.  6 — 7 

S.  GRACILE  Reinsch  pi.  57,  f.  5 

S.  WESTII  G.  M.  Smith  pi.  37,  f.  8—10 
Selenosphaerium  americanum  Bohlin. 

SIPHONOCLADIALES 

SORASTRUM  Ktz 

S.  AMERICANUM  (Bohlin)  Schmidle 

pl.  44,  f.  7 

UNDULATUM  G.  M.  Smith 

pi.  44,  f.  2—5 

S.  SPINULOSUM  Nag.  pi.  44,  f.  4—5. 

SPHAEROCTSTIS  Chodat  

S.  SCHOETERI  Chodat  pi.  19,  f.  3—4. 

SPIROGYRA  Link  

S.  PORTICALIS  (Mueller)  Cleve 

pi.  51,  f.  3 

SPIRULINA  Turpin  

S.  MAJOR  Ktz.  pi.  7,  f.  7 

S.  FRINCEPS  (W.  & G.  S.  West) 

G.  S.  West  pi.  7,  £.  2 

Staurogenia  apiculata  Lemm 

8.  cruciatum  Wolle 

8.  crucifera  Wolle 

8.  fenestrata  Schmidle 

8.  Lauterhomei  Schmidle  

8.  multiseta  v.  punctata  Schmidle  . . . 

8.  tetrapedia  Kirchner  

8.  triangularis  Chodat  

STIGEOCLONIUM  Ktz 

S.  LUBRICUM  (Dillwyn)  Ktz. 

pi.  50,  £.  7 

SYNURA  Ehr 

S.  UVELLA  Ehr.  pi.  12,  f.  9—10 

Tetracoccus  botryoides  W.  West 


133 

133 

133 

163 

182 

162 


163 

163 

163 

101 

101 

185 

185 

49 

50 

50 

146 
145 
145 
148 
148 

147 
147 
147 
180 

180 

70 


120 

121 


123 


(Reinsch)  de  Toni  pi.  23,  f.  10—13.  116 
T.  PENTAERUICUM  W.  & G.  S. 

West  pi.  25,  f.  75—77 

V.  minimum  W.  & G.  S.  West 
T.  PLANCTONICUM  G.  M.  Smith 

pi.  27,  f.  4—5 

r.  proteiforme  G.  M.  Smith  non  (Turn.) 

Brunnthaler  

T.  REGULARE  Ktz.  pi.  24,  f.  74 H8 

T.  regulare  Chodat  non  Ktz 119 

V.  INCUS  Telling  pi.  24,  f.  15—76.  118 
V.  TORSUM  (Turner)  Brunn- 
thaler pi.  24,  f.  77—78 119 

T.  spinulosum  Schmidle  124 

T.  TRIGONUM  (Nag.)  Hansg. 

pi.  23,  f.  74 — 16 117 

V.  GRACILE  (Reinsch)  de  Toni 

pi.  24,  f.  5—9 117 

V.  SETIGERUM  (Archer)  Lemm. 

pi.  24,  f.  7—4 117 

T.  VERRUCOSUM  G.  M.  Smith 

pi.  25,  f.  2—3 

T.  VICTORIEAE  Wolos 

V.  MAJOR  G.  M.  Smith  pi.  24, 

f.  79 — 22;  pi.  25,  f.  7 H9 

Tetrapedia  emarginata  SchrOder 147 

T.  pentaedricum  Chodat 129 

T.  setigera  Archer H7 

TETRASPORA  Link  192 

T.  LACUSTRIS  Lemm.  pi.  79,  f.  5 — 6.  102 

TETRASTRUM  Chodat 149 

70  jr.  wpiculatum  (Lemm.)  Brunnthaler. . 146 
197  T.  mwZtisetwm  (Schmidle)  Chodat  ....147 


119 

119 


INDEX 


243 


Page 


T.  STAUROGENIAEFORME 

(Schroder)  Lemm.  pi.  S7^  f.  5 — 6.  149 

TRICHODESMIUM  Ehr 64 

T.  LACUSTRE  Klebahn  pi.  8,  f.  1 54 

TRIBONEMA  Derbes  et  Sober 87 

T.  BOMBYCINA  v.  DEPAUPERATA 

Wille  87 

T.  MINUS  (Wille)  Hazen 

pi.  15,  f.  n — 18 87 

TRIBONEMACEAE  87 

Triehomes 48 

TROCHISCIA  Ktz 108 

T.  RETICULARIS  (Reinsch)  Hansg. 

pi.  22,  f.  2 109 

Tychoplankton 1 

ULOTRICHACEAE  178 

ULTRICHALES  178 

ULOTHRIX  Ktz 179 

U.  SUBCONSTRICTA  G.  S.  West 

pi.  50,  f.  -J— 5 179 

U.  ZONATA  (Weber  & Mohr)  Ktz. 

pi.  50,  f.  6 179 


Page 


XJroglena  americana  Calkins  71 

UROGLENOPSIS  Lemm 71 

U.  AMERICANA  (Calkins)  Lemm. 

pi.  18,  f.  1—4 71 

VOLVOCACEAE  93 

VOLVOCALES 89 

VOLVOX  L 97 

V.  AUREUS  Ehr.  pi.  18,  f.  2 98 

V.  GLOBATOR  L.  pi.  18,  f.  3—5 98 

V. lMONONAE  G.  M.  Smith,  pi.  18,  f.  1 99 

WESTELLA  de  Wildeman 106 

W.  BOTRYOIDES  (W.  West)  de 

Wildeman  pi.  21,  f.  ^ 107 

V.  MAJOR  G.  M.  Smith 107 

W.  LINEARIS  G.  M.  Smith 

pi.  21,  f.  2—3 107 

Zooplankton  1 

ZYGNEMA  C.  A.  Ag 184 

Z.  PECTINATUM  (Vaucher)  C.  A. 

Ag.  pi.  51,  f.  2 185 

ZYGNEMACEAE  183 


